Perhaps that could be true for some, but I don't see how becoming sedevacantist would necessitate to switch chapels (unless you hold to absurd dogmatic non-una cuм position) - Resistance and SSPX priests also offer valid sacraments and Catholic teaching. In our SSPX chapel we have sedevacantists who are perfectly happy to attend the Mass and actively support the parish even though they disagree with the SSPX on the status of V2 claimants. There are also perfectly good and rational reasons for not embracing sedevacantist position, such as the problem of Apostolic succession and Ecclesia-vacantism which is a logical conclusion of sedevacantism (even if sedes deny that).
I agree with Matthew that the current crisis is a mystery and no theologian ever proposed a satisfying explanation for what is going on today. Both R&R and sedevacantist positions have their weaknesses, they both deny indefectibility of the Church, although in different ways (R&R through asserting that an Ecuмenical Council can teach grave error to the Universal Church, sedevacantists through asserting that all episcopal sees are vacant, which means Ecclesia-vacantism and the end of Apostolic succession).
However, it is not quite true that the Church never taught anything relevant to the current crisis. The Church most certainly teaches that a formal heretic loses membership in the Church and is outside the Church. Thus, if V2 claimants to the Papacy are formal heretics, they cannot be Popes, unless you want to argue that one can be outside the Church and remain Pope.
Holy smokes, where do I even begin responding to this post? Reasons to switch chapels if someone becomes a sedevacantist? How many answers do you want?
First, the SSPX accepts Novus ordo priests into their ranks without conditional ordination. The new rite of ordination is doubtful at best, so these "priests" are providing doubtful sacraments, and they are scattered all throughout the SSPX. I would switch for this reason ALONE. Second, the SSPX tells their congregations to disregard the man they think is the Pope, which is schismatic by definition. Another reason to switch. Third, the SSPX teaches General Councils (always infallible) can teach error. I could go on.
You admit the Church teaches a heretical Pope loses membership in the Church, then in the same post you say the current crisis is a mystery with no satisfying explanation. Major contradiction. If you know the Church has taught this, why are you resisting the Church? Francis has taught even against the Natural Law which no one can claim ignorance of, so this can only be labeled formal heresy. This means the teaching of the Church takes effect; Francis has lost membership.
You also say both R&R and sedevacantist positions "have their weaknesses". ONE and only ONE position has to be true, which leaves any others false. 2+2=4 is true, and all other answers are false, but no one in their right mind would say, "2+2=4 has its weaknesses" - it's either true or it's not. If R&R is true, sedevacantism is false, and vice versa.