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Indefectibility means the Church, as an organization, will last til the end of time.  It has nothing to do with the purity of the Church's teachings, which is related to infallibility.  You can't mix and match these two characters.
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We are supposed to follow the UNIVERSAL magisterium (i.e. what has always been taught), not simply the current magisterium (which is fallible).  That's why it's called "Tradition" because it follows the maxim:  ubique, semper, et ab omnibus  (as St Vincent below explains).
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St. Vincent of Lerins - “Moreover, in the Church itself, all possible care must be taken that we hold that faith which has been believed everywhere, always, and by all.”
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If the current magisterium deviates from Tradition, they are anathema.  V2 is not imposed on any catholic under pain of sin; it is part of the ordinary/fallible magisterium.  This in no way impairs indefectibility because the continuance of the Church is not dependent upon the sanctity or orthodoxy of its Cardinals (including the hierarchy) but it depends on the organizational structure surviving which includes the lower clergy and laity.  As St Athanasius said during the Arian heresy, when 95% of the catholic world was heretical (including most of the hierarchy):
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"Even if Catholics faithful to Tradition are reduced to a handful, they are the ones who are the true Church of Jesus Christ."
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Currently, we are in the same predicament (and worse) than during the Arian crisis.  99% of the hierarchy/laity are heretics.  Those catholics who hold the pure, unblemished Faith are very few.  The Church still exists in these few, as Christ promised.

Indefectibility means that the Church will, until the end of time, remain essentially what She is. Many principles of the Church come from indefectibility (Disciplinary Infallibility, for example). She will never give something contrary to the Deposit of Faith/Gospel. This is exactly why the idea of Magisterium having to "conform" to Tradition is strange + novel. If it came from the authority of the Church, it's already known that it cannot be contrary to the Faith. Vatican II expresses a neoteric modernist faith; and thus falls under Saint Paul's anathema. From the blogspot article I linked (the writing of Fenton)--it's clear that there is never a reason to not submit to Ordinary Magisterium, though fallible, because it's impossible that Magisterium could cause one to embrace anything false... and this derives from indefectibility. There is nothing contrary to indefectibility in saying that we haven’t had a pope since the death of Pope Pius XII in 1958 (It's absolutely specious to say that Vatican I condemns our theological position); and succession continues as CT posits. There were times during the Arian crisis, in which there were areas of Catholics without a non-heretical Bishop governing... the Church did not defect in its mission of teaching, governing and sanctifying then, because of the faithful remnant. But it *is* contrary to the indefectibility of the Catholic Church to say that true Popes could promulgate V2, officially endorse ecuмenism, promulgate the Novus Ordo, 1983 Canon Law, etc. And to concede that the Pope can be a heretic YET have ministry in the Church means that the gates of hell have prevailed:

Pope Vigilius, Second Council of Constantinople, 553: “… we bear in mind what was promised about the holy Church and Him who said the gates of Hell will not prevail against it (by these we understand the death-dealing tongues of heretics)…”

Pope St. Leo IX, Sept. 2, 1053: “The holy Church built upon a rock, that is Christ, and upon Peter… because by the gates of Hell, that is, by the disputations of heretics which lead the vain to destruction, it would never be overcome.”

St. Thomas Aquinas (+1262): “Wisdom may fill the hearts of the faithful, and put to silence the dread folly of heretics, fittingly referred to as the gates of Hell.” (Intro. To Catena Aurea.)

And again, V2 is either UOM or Extraordinary Magisterium--infallible if Paul VI was Pope. It does not matter how many statements we can find of its alleged "pastoral" nature. We cannot invent a new theology of the Church just to acknowledge Francis. If we entertain that we can somehow reject it while it coming from the authority of the Church, we still have the problem of canonizations/NOM/errors in the 1983 Canon Law--they're supposed to be protected as a secondary object of the Church's infallibility.

Ah yes, only in the R&R could 99% of masses being invalid and "blasphemous", along with the clergy and pope teaching universal salvation and communion for divorceés among many other heresies, not constitute leading souls to hell.

People will *not* be lead at all to where they do not want to go, at least not for very long. To put it another way, people will only be led to where they want to go - that is simply the nature of our free will, that's how free will works - we do whatever it is we want to do.  

Why is it that *you* don't believe the errors and heresies taught by the clergy and conciliar popes, but (figuratively speaking) everyone else does?

This question is a core question as relates the title of this thread.

No power on earth will get *you* to follow the heresies taught by the pope and clergy against your will, no power on earth will get you to attend the NO service against your will, no power on earth can make you sin against your will, and no power on earth can lead your soul to hell unless you make a conscience decision of your own free will that you're content to go there - so why is it that you believe everyone else (figuratively speaking) can be led to hell by the conciliar popes and clergy, but not *you*?

Argument 1
1.  If a teaching/promulgation is not binding either a) under pain of sin, or b) with certainty of faith,
        then the Church's doctrine hasn't changed and this "teaching"/promulgation has nothing to do with infallibility/indefectibility.
2.  V2 & the new mass do not have to be accepted 1) under pain of sin, or 2) with certainty of faith.
     a.  V2 = theological speculation/quasi-heresy.
     b.  New Mass = quasi-heretical liturgy.
3.  Ergo, V2 and the new mass have nothing to do with infallibility/indefectibility, because the Church does not force anyone to accept/attend them.

The vast majority of Catholics are told must attend the NO under pain of mortal sin(no NO clergyman will tell you that you can stay at home as long as there's no Latin mass nearby). So yes, the attendance of the new mass is binding under pain of sin.

Argument 2
4.  Scripture, Tradition and Doctrine are binding on all Catholics, 1) under pain of sin and with 2) certainty of faith.
5.  Scripture, Tradition and Doctrine, as explained/taught by the Church, are 100% required for salvation.
6.  V2 and the new mass are optional and not required for salvation.
7.  V2 and the new mass are not part of the Church's official theology or Her official liturgy.
8.  Ergo, these novelties have nothing to do with infallibility/indefectibility, because the Church does not force anyone to accept/attend them.

Ecuмenical Councils are absolutely not optional, for one. The new mass being optional is your personal layman opinion which completely contradicts what the pope or any NO clergyman have said.

Argument 3a
9.   Quo Primum's law is still in force, as confirmed by Pope Benedict in 2007.
10.  QP commands all of the latin rite to use its missal (1962).  QP does not allow anyone to revise its missal.  Both of these commands under pain of grave sin.
11.  The new mass is illegal to attend because it violates QP.
12.  The new mass is not approved by the Church, no matter how many V2 popes use the new missal or promote it publicly.
13.  A pope can violate Quo Primum, just like any Catholic.  A pope is not above the law, and he must abide by it, if he fails to change it.
14.  Since no pope has changed QP, all popes who say, attend or promote the new mass are promoting an illegal and sinful act.
15.  The new mass' existence is not a violation of indefectibilty because it is, and always has been, illegal and therefore sinful.

QP does not forbid the pope to revise the missal, popes have done it many time before - it's order to not revise the missal is directed at bishops and priests to ensure the mass wasn't being altered in any individual dioceses/parishes.

Popes can of course violate canon law, but not when they're making laws. New laws override old laws.