Sedevacantism is a schism. The Chair of Peter is NOT empty. There have been men with the authority of the Vicar of Christ in the Vatican since 1968. This is just a new form of division that Satan is enacting in our battered and bloodied Church.
Furthermore, I have a prediction:
Sedevacantism will never ever go away. It will linger in existence until the return of Jesus Christ. Further, sedevacantists will grow in their hatred for the True Church as the decades roll by. The very mention of the Catholic Church will cause instantaneous scoffing, eye rolling, and sneering.
Loyal sedevacantist followers will never be satisfied. There will never be anyone arising from anywhere to do anything they want. Ever. If the pope is fake, and if the cardinals are wrong, and the bishops are corrupt, then just where is a legitimate pope supposed to arise from?
Another prediction: sedevacantism will grow in its members. You can look forward to many societies, clubs, conferences, and publications. The Devil likes to have as many opposition groups against the Universal Church of God as possible. There will be people who convert directly into sedevacantism without ever having sworn any kind of fealty to the Mother Church. This is because the idea of being in opposition to the big bad loony popes of old will be an attractive prospect, courtesy of our anti-Christian media.
In a hundred years or more--if the world lasts that long--sedevacantists will still be around enjoying the same status as Eastern Orthodox. Meanwhile, the real news will be what is happening in the Catholic Church that the sedes departed from.