1) The Sedes would rally around that true Pope because he will have confirmed what they already believe.

2) The Sedes would submit themselves to the true Pope's judgment in the matter because they know that a true Pope is guided by Jesus Christ. Again, you said this man would be a "true Pope." Let's say there was a miraculous sign that confirmed his status as such. If a Sede did not submit to him, they would betray their own principles.

Thank you, good answer.

Again, Sedevacantism is nothing more than an opinion that tries to make sense of the Crisis. It is not a dogma. But it is not formally inconsistent with Catholic dogma. The version of R&R that claims that the true Popes can be "heretics" while continuing to be true Popes is formally inconsistent with Catholic dogma.

Yes, sedeism is nothing more than an opinion, the problem with that opinion is that for most who've convinced themselves that their opinion is fact, it is no longer an opinion, it becomes a binding dogma of the Church wherein all those who do not agree with that dogma are low life heretics.
 
There are valid arguments re: heretics can/cannot be popes on both sides. In one of his talks, Fr. Hesse makes some sense of it from a non-sede point of view, but in the end, whether they're popes or not, there. is. nothing. anyone. can. do. about. it - anymore than anyone can make the sun shine on a cloudy day. Which, like St. Francis in the OP, is why non-sedes do not dwell on the idea, and like St. Francis in the OP, are content to leave the matter up to the Church, in her own good time. 

Then there's the dogma stating "that it is absolutely necessary for salvation that every human creature be subject to the Roman Pontiff."
Referencing, as I have already done in this thread, St. Thomas More's last words, non-sedes absolutely, positively and unequivocally achieve this even if the pope is a lying, modernist, no good thieving apostate, murderer, adulterer, commie heretic.

But for sedes whose opinion had morphed into dogmatic certainty, the reality is that they can only rely on their opinion/conclusion to be right. For non-sedes, the price is too high, that's too much to risk on our opinion. Leave it up to the Church.   

So we agree that a future "true Pope" would have to condemn V2?

Only if he is going to restore the Church.