I could in theory become a Benedictine just by adopting the Benedictine rule (although I believe they may have to be celibate).  What would you say regarding the status of Benedictines (which have never operated like most Orders) ... since you're much more versed in Church law in this regard?

The OSB is one of the few cases where trad monks and nuns could slip by through a lacuna in ecclesiastical law, at least prior to the 1983 Code. The monks and nuns would be real Benedictines; their oblates would be real third order. Things are not quite as clear with the 83 Code since it has corralled in many privileges and autonomies that once existed in law. I would need to check the current law for certainty with the OSB.

That's interesting because I read somewhere on the Diamonds' website (can't find it now) that Our Lord promised that the Benedictine Order would endure until the end of time. What you say here would be consistent with that promise.

Has the same promise been made to the Franciscan order? I think I remember reading that on this forum. Does anybody know? That's precisely the order I'm interested in.

That promise was made to the Franciscan order, yes.  I am a third order Franciscan under Fr Francis Miller OFM and the brothers in Brazil.  The question of indulgences, general absolution, and other privileges is disputed.  One solution was described well above.  Another possibility follows from sedevacantism.  Admittedly it is difficult to prove.

The vast majority of Franciscans followed the modernist hierarchy and thus objectively no longer profess the Catholic religion in its integrity.  Moreover those appointed as superiors prior to the changes have died off.  Bishop (then Father) Vizelis was not a superior but was a solemnly professed OFM priest when he abandoned his Novus Ordo Friary and began receiving requests to receive novices.  Since no Franciscan superior designated to receive vows abandoned conciliarism to continue the Order, it can be alleged that epikeia supplied Bp Vizelis with the power to receive vows.  (It is evidently not the mind of the legislator to have the Franciscan Order die out entirely due to the defection of its leaders.)

It is a fact that Bp Vizelis received the vows of Fr Francis and that Fr Francis in turn received the vows of Fr Peger in Brazil, who received the vows of those brothers who have made vows over there.  It is possible to contend that this thread of continuity in the face of the near-total defection of the Order is sufficient to make the (solemn) vows valid.  The validity or invalidity of the solemn vows as well as the privileges of both he first and third orders follow from whether or not the Franciscans today constitute the OFM as such.  

I will say that the brothers in general do not believe this theory to be true, which is why they use the term "OFMsub" (sunsequentes) to indicate that they are following the rule, yet make no claim to legal continuity despite having a moral continuity.

It's worth noting that Fr Martin Stepanich OFM STD (another Franciscan who left his Friary after the changes were imposed) also received many Third Order members, who are now under Fr Francis.  He also recognized the title of OFM belonging to Fr Francis through Bishop Vezelis.

Ultimately it's an academic question.  The rule itself is what will benefit your soul more than any privileges, which were granted long after the establishment of the Third Order.

I will say that the brothers in general do not believe this theory to be true, which is why they use the term "OFMsub" (sunsequentes) to indicate that they are following the rule, yet make no claim to legal continuity despite having a moral continuity.

What a coincidence! Just the other day, I was researching what Fr. Miller's "sub" meant. I found out that it meant "subsequentes" but not the reason behind it. I like his honesty and humility for that.

Thank you for your post, it's very informative and objective. Also, thanks to Elwin Ransom for very good posts as well.

As for me, I'll probably join a Franciscan Third Order. Despite the canonical mess we have on Earth, there is a Good God in Heaven that loves the virtue that comes with following the rule.

Ave Maria Purisima

As for me, I'll probably join a Franciscan Third Order. 

Do it!  There is no Religious Order with as many canonized Saints as the Franciscan Order.  All the recent popes from Leo XIII to Pius XII-  the Popes of the great encyclical- were Franciscan Tertiaries.  Pope Leo XIII said that the Third Order of Sr Francis would save the Church.  Oh and a side note: I hear people call Fr. Francis "Fr. Miller" a lot since it is proper to address a secular priest by his last name.  Religious priests however should be addressed by the name they received in Religion.  I know its confusing but technically the proper form of address is "Fr. Francis."  Not that he would care of course.  Ave Maria Purisima sin pecado concebida.

Sermon on the religious state
by His Excellency Archbishop Marcel Lefebvre
April 27, 1981
on the occasion of a religious profession of Father Innocent-Marie OP in the church of the convent of La Haye-aux-Bonshommes:

In the name of the Father, and of the Son and of the Holy Spirit, so be it. My dear friends, my dear brothers,
It is with great joy and satisfaction that we find ourselves today in this church to assist and support the resurrection - if one can say so - of the Dominican Order in our country of France.
*
We are obliged to note - without, however, spreading bitter criticism - but to note, quite simply, the facts: authorized persons tell us that religious orders today are, alas, in the midst of self-destruction, in the midst of decadence. Why is this so? Particularly because they have abandoned the very bases and foundations of what made their orders prosper. The particular grace of founders such as St. Dominic, St. Francis of Assisi and St. Benedict, had allowed for the writing of constitutions, statutes, laws, which founded these orders on a particular holiness in the Church. Now, since - it must be said - since the Second Vatican Council, the general chapters that were requested by the Holy See in order to update, as has been said, the aggiornamento, of these constitutions, of these religious orders, have simply produced the ruin of these constitutions, a change so profound in the spirit of these orders and congregations, that we are now witnessing their ruin and their disappearance.
Faced with the truly painful state of these religious orders and the situation in which the Church finds itself today, should we simply remain silent and inactive? Or, on the contrary, do those who are aware of this destruction, of this disappearance of the works of holiness in the Church, not have the duty to preserve and revive what has been the glory of the Church, and what is a proof of the Church's principal note: holiness?
*
I believe that it can be said in truth that the Catholic Church without religious orders, without these religious professions, would no longer be the Catholic Church. The manifestation that took place, immediately after the death of Our Lord himself, of those people who wanted to consecrate themselves in a total way to Our Lord Jesus Christ, distancing themselves from the world and having as their only desire to contemplate and meditate on the heavenly things, the lasting things, the eternal things, instead of attaching themselves to the ephemeral and decaying things of this passing world, manifests precisely the holiness of Our Lord Jesus Christ.
There have been many hermits who have populated deserts, hermits who have been seized by the spirit of Our Lord Jesus Christ and have distanced themselves from the world.
And then came the Cenobites, especially with St. Benedict who spread throughout the world those monasteries of which we still see today such admirable remains in all the countries of Europe: if we mark on a map of Europe the Benedictine monasteries, then later the Cistercian monasteries, we will see that Europe was covered with these monasteries, thus showing that many souls were captivated by Our Lord Jesus Christ, attracted by Our Lord Jesus Christ to live in union with Our Lord in order to better devote themselves to the service of souls and the Church, Contemplative souls who shut themselves up forever until their last breath in cloisters, in monasteries, in order to meditate on the charity of Our Lord Jesus Christ, on his cross, on his holy passion, and to live a life of privation, of penance, in order to better love Our Lord Jesus Christ, so that the charity of Our Lord Jesus Christ may be more present in them.
Without doubt, these contemplative congregations do not have the external apostolate as their goal, but their apostolate was no less effective: the example, the only example, of these people shutting themselves up for their entire lives in cloisters and monasteries in order to live in union with Our Lord Jesus Christ was a magnificent example for Christians in the world, and it encouraged them to live also, in other situations, with Our Lord Jesus Christ and following Our Lord.
And then came orders that were called mixed, in the sense that they had both a part of their life dedicated to contemplation and a part of their life dedicated to the apostolate. And it was particularly St. Dominic and St. Francis who realized these societies, these orders that devote themselves at the same time to study, to prayer, to the religious office, to the liturgical office, and that also go about preaching the Gospel, attracting to Our Lord Jesus Christ the crowds of those who so easily turn away from it, attracted by the mirages of this world, attracted by the pleasures and voluptuousness of this poor world.
*
And that is why these religious take the three vows of poverty, chastity and obedience, in order to remove all obstacles that may be in their way and that would prevent them from being deeply and totally attached to Our Lord Jesus Christ. For it is not only to manifest a spirit of penitence and renunciation of the world that they take these vows - vows which may appear to the world as folly, especially to those who do not believe in Our Lord Jesus Christ. To the pagans - gentibus stultitia, said St. Paul - the cross of Our Lord, for those who do not believe, is folly. Pro Judaeis scandalum: for the Jews, it was a scandal that this cross to which their Messiah, their King, was attached - it is not possible! Pro credentibus autem, sapientia Dei: for those who believe, it is the wisdom of God. Yes, it is wisdom to remove from one's heart everything that can be an obstacle to the love of Our Lord Jesus Christ and, for those souls who want to consecrate themselves to Our Lord, to do so in an official, public way, in the Church, before the Church; and that is why those who take the three vows of poverty, chastity and obedience before the Church are religious in the Church
Vow of poverty: which keeps them away from those earthly goods which, so easily, can procure forbidden joys and draw us into sin.
Vow of chastity: because they want their hearts to be undivided. Oh, certainly, one can be sanctified in the ways of marriage, and how many souls have been sanctified, united to Our Lord Jesus Christ! But it must be recognized that there are also opportunities, unfortunately, to distance oneself from Our Lord Jesus Christ, perhaps more frequent and easier than for those who live far from the pleasures of the flesh and who renounce making a home here below. It is the honor of Christian families to give their children to God: there is no greater grace for a Christian home than to have a religious in its home!
Then, the vow of obedience, which is perhaps the most difficult to fulfill: it is perhaps easier to abandon the goods of this world, not to make a home in this world, than to abandon one's own will. Not to be free anymore, to be in the hands of a superior who will show you the way of God which is to be followed all along your existence, that is very difficult. And yet, this is what the religious does: he puts his will in the hands of his superior in such a way that his superior will dispose of him for his apostolate, for the functions, the duties that he will have to fulfill.
That is what a religious is before the Church. But, once again, these vows which may seem austere - giving up all financial provision, giving up the joys of making a home, giving up one's own will - are they not very austere, and a life of penance which is very unbearable? - Well, no! When these renunciations, when this abnegation is made in order to give oneself to Our Lord Jesus Christ, then, on the contrary, it is a profound joy and a consolation that religious experience in an intimate and profound way within their souls. If God came among us, if he wanted to become incarnate, if he wanted to live among us and give all his blood and his life for the redemption of our souls, he who is God gives extraordinary consolations and graces to the souls who give themselves to him.
*
Thus, in a few moments, my dear friend, you will pronounce these vows of religion in circuмstances that are, moreover, quite particular. It is true that I have not received a special delegation from the Superior General of the Dominican Order to receive these vows that you are going to pronounce, and that, consequently, one can say that these vows in the eyes of the Church are not public vows, but private vows. But should we, as even some of our friends have advised, renounce them? Should we renounce the revival of Dominican life in souls who wish to follow the way of Saint Dominic? I do not think so. And I believe that, as some of our friends who are in Rome and well placed in the Roman Congregations have said: "If you do not follow the letter of the Law, you follow its fundamental laws. Indeed, the legislation of the Church has, in its principles, to be made entirely for the salvation of souls: prima lex, salus animarum, the first law in the Church is the salvation of souls.
Then, in certain circuмstances, historical circuмstances that do not depend on us, of which we are only witnesses, appalled witnesses, stunned witnesses, painfully surprised, we have the duty to provide for the salvation of souls. And this is the duty of every priest, of every bishop. And that is why, if in these circuмstances the letter of the law is against us, the fundamental laws of Law are for us. Because, as I said a moment ago, the Church cannot do without religious orders! The Church cannot do without the witness of its holiness. The Church would no longer be holy if there were no souls who consecrated themselves to God in a definitive way. If there were no more Carmelites, if there were no more Benedictines, if there were no more Dominicans, no more Jesuits, no more religious orders, well, the Church would no longer manifest its holiness. This is an essential note of the Church. And it is the most convincing; for simple souls, it is the holiness of the Church that is more important than all the other notes and that is more apparent, and more attractive. Simple souls are convinced by this holiness which is manifested in souls who consecrate themselves to God.
So we think it is quite legitimate, my dear friends, that you should gather here and ask St. Dominic to give you the grace of his Order, following his principles, the principles that St. Dominic put in his Constitutions, in order to give back to the Order of St. Dominic its true sanctity and the true purpose for which St. Dominic founded it.
*
And what is this goal, in a few words? I think it was St. Thomas Aquinas, son of St. Dominic, who defined it best: Contemplata aliis tradere, to communicate to others the object of your contemplation, that is to say, the object of your studies, the object of your meditations, the object of your prayers, the object of your orisons; whatever the good God inspires in you by this prayer, by this study, to manifest it to others; to preach the Gospel, to go and preach Our Lord Jesus Christ! This love of Our Lord Jesus Christ which will inflame your heart and soul like the soul of St. Francis and St. Dominic, well, you will go and spread it in the world. And these graces that will be spread in the world will bear fruit in souls. This is what you will do, this is what your program will be, so well defined by St. Thomas Aquinas.
So we sincerely hope that you will take up the torch of all the ancestors, of all the saints who followed Saint Dominic; and that the Church in a few years, perhaps soon, will rejoice and congratulate you. And you know it well yourself, you have already met Dominican fathers who, here and there, sorry to see their Order destroying itself, encourage you and tell you: "You are right, continue, hold on!"
Well, I am convinced that the grace of God will also be with you, and that vocations will come, and that this house will know a real prosperity, and that it will be a radiance not only for this region, but for all of France. When we think of what the children of St. Dominic have done in South America, for example, it is admirable! Together with the children of St. Francis, they are the ones who converted all the countries of South America. I was in Mexico last January and I could see: [there are] Dominican convents and Franciscan convents everywhere in this land. In spite of the persecutions that have taken place in this poor country of Mexico for the last fifty years - the convents were demolished, the priests and religious men and women were killed, the congregations were driven out - there are still admirable vestiges of this presence: it was they who converted these pagan populations.
So, since we are in a time when it is necessary to convert again, well, you will be these apostles, apostles of both the great and the small, you will go to carry this grace of the Gospel which will make our France a Christian France again!
Today, my dear brothers, we will ask in a very special way during this holy mass, all of us together and all of you gathered here, we will ask that St. Dominic come to this house and precede the Blessed Virgin Mary, the Virgin Mary in whom he had so much devotion, he who spread the practice of the Rosary in such a fervent way. You too will be devotees of the Virgin Mary! She will protect you and help you in your preaching for the greater good of souls and for the greater glory of the Church.
In the name of the Father and of the Son and of the Holy Spirit, so be it.