If you elect your own Pope you are called a Conclavist. SomeMost sedevacantists think that the "endgame" is Judgment Day. Other sedevacantists (e.g., Fr. Cekada here, p. 14, appendix 5) do not rule out a miraculous appointment/election of a true pope. Several visionaries have prophesied such a scenario (cf. this).
So why would anyone believe this?
The real 3rd Secret of Fatima is about the apostasy of the heirarchy, additionally, Sister Lucia said it the end times were upon us.
Full version of the Prayer to St. Michael composed by Pope St. Leo the Great indicates apostasy in Rome with the words:
In the Holy Place itself, where has been set up the See of the most holy Peter and the Chair of Truth for the light of the world, they have raised the throne of their abominable impiety, with the iniquitous design that when the Pastor has been struck, the sheep may be scattered.
It is the message of Our Lady of LaSalette
A counterfeit church is set up in the Book of Revelation (Whore of Babylon is the spiritual counterfeit of the Bride of Christ)
You've already mentioned the Prophecy of the Popes of St Malachi which ends with "dreadful judge will judge his people. The End"
Revelation 12:1 is talking about the The Miracle of the Sun in Fatima (which means in 1917 already we were pretty far into the Book of Revelation)
There's quite a bit more interesting points that would be lost of the general reader like, the connection between the Maccabees, and the parallels between the first Antipope John XXIII and the modern one, the curse in Quo Primum on deviations of the Tridentine Mass, the parallel between the changes in the New Mass and Cranmer's changes, the significance of Apostolicae Curae in relation to the changes to the new rite of Ordination, the relationship of the 7 kings in Revelation and the new lines of kings created by the Lateran Treaty on February 11, 1929.
Or are they content to remain as an elite minority while everybody else is condemned?
This is an uninformed question, since sedevacantists are active in proselytization of their views, meanwhile Antipope Francis refers to proselytization as "Solemn Nonsense" and just asserts that everyone should follow their own conscience, and the "church" should stop obsessing over abortion, gays, and contraception.
He's gonna even more big changes in October apparently, I'm interested to see what he does.