A lot of the citations about the ability of the Church to exit Rome used to defend sedevacantists are very, very poor. For instance, Cardinal Billot's quotes are usually used to defend an imperfect council to elect a new Pope, but Billot actually implies a need for the election to be done with Roman clergy, whereas, since there is no ordinary jurisdiction and no actual Roman clergy left with the sedevacantist ones (or SSPX ones for that matter), it doesn't seem possible to elect a Pope. Plus, the sedevacantists don't even agree as to whether or not most of their clergy are heretics concerning Baptism of Desire and Invincible Ignorance, and many sedevacantists have flat out excommunicated one another. Their ecclesiology is probably even worse off than the Orthodox.
I will take this paragraph as an example. Sedevacantism doesn't have anything to do with the Church "exiting" Rome.
There are several opinions about what would happen if all the cardinals died, none of which is fundamental to sedevacantism, nor does it refute it.
Ordinary jurisdiction isn't undisputedly necessary for a legitimate papal election. And this concern doesn't even apply to sedeprivationism.
As for there being "no actual Roman clergy," several theologians do hold that an Imperfect Council could elect a Pope in that case. And, once again, this does not apply to sedeprivationism.
Very few sedevacantists are divided on the "Baptism of Desire" question. 99% of sedevacantists are the ones most violently opposed to Feeneyism. You have only the Dimonds who combine sedevacantism and Feeneyism.
And, would you please stop dabbling with Eastern Orthodoxy lest you end up losing your faith and your soul. There's absolutely no way in which their ecclesiology is "worse off than the Orthodox." Orthodox are at once schismatics and heretics with nothing even approaching a Catholic ecclesiology?
Just this one paragraph is such a hot mess that you need to go back to the drawing board and study the basics of the Catholic faith (i.e. vs. Orthodoxy) before weighing in so confidently on a complex topic.