If someone can converse with Pope Francis and get him to admit his belief that the church taught one thing, and admit his teaching or belief in something contrary, then you've got him in formal heresy, as best as I understand it. The the question is, who's going to do anything worth while about that formal heresy? Who's going to elect a non heretic pope to replace him? At least clear formal heresy would make it a lot easier for many to become sedevacantists.
I don't see any reason to "become sedevacantist." I mean, aside from separating myself from non-sedevacantists and maybe joining the others who've done the same, declare "I'm a sedevacantist" and stop praying for the man, what would be the point?
Correct me if I'm wrong here, but....
Fr. Hesse first admits that someone of higher authority needs to officially declare the pope lost his office.
He then said that there is no authority on earth able to officially declare that the pope lost his office.
Then he said that before he could go sede that he would need scientific, indisputable and absolute proof he is no longer pope, and that if he had that proof he would then join the sedevacantists.
It sounds to me that he really does not need that authority that he said was needed, which is to say because there is no authority, all he needs is proof meeting his criteria, then he becomes that authority he said was needed - which is already the exact same path taken by the sedes.
I dunno, to me and many other trads, dealing with this issue is nothing more than the most basic, fundamental Catholic theology: The pope / man called pope is a heretic, as such we cannot obey or follow him in his heresies regardless of whether or not he is the pope, or whether he lost his office. So what's the point, what is the advantage of becoming sedevacantist?