For example, say Pope Benedict “reveals himself” to be a heretic tomorrow - we can assume he would never dare publish anything too crazy, the heresy would be something quite minor. He might say Jesus’ Divinity didn’t include His hair…
He could never proclaim that as an infallible dogma, because it just doesn’t qualify as one of those teachings. We’d simply let him wallow in his own heresy for however many years, and when he died, the next pope, we would pray, would then state ALL of Jesus was Divine, including His hair.
You might say: “well, changing the liturgy is more important that that!” And I would say: “the ‘bad’ changes have been made by YOU in society, by allowing such things as guitars and bad architecture to invade the Church.” Don’t blame some bishops 40+ years ago for YOUR ugly parish church. Don’t blame them for wishy-washy homilies, don’t blame them for the ecumenicism/indifferentism that plagues the Church, don’t blame them for the ills of modern society - blame modern society!
In short, there is no merit to Sedevacantism; it is a “cop-out”, it is used by people that don’t want to face the real world, they don’t want to face a culture that is SICK, they want to pretend to be “back in the good ole days”. We live in an especially SICK society here in the United States, and it isn’t much better in France, and it’s really not all that much better in even Bavaria or Poland, and it’s getting worse in Spain and Portugal. The situations in Mexico, Central and South America are so far removed from our own in the West, it would be difficult to even convince people of the Sedevacantist frame of mind - I honestly believe it is a luxury of the West for people to even explore such novelties.
Instead of running around crying that the Holy See is vacant, why not run around and harass heretical priests and bishops? Why not continue to evangelize and instruct people in the Faith? Why not make it a point to go to Daily Mass at your local parish? Quit playing games, and join the real world: that’s what I say to the Sedevacantists and the like.