Goose, in Athanasius' time, few bishops and preists held to the True Faith, most were deceivers or decieved...the situation is far more complex then you are describing......who held on for yrs, often under terrible persecution, ridicule,etc?? ABL and the SSPX.....ABL in many ways is the Athanasius of our times........
Why should Fellay regularize with modernists and heretics? for what purpose would that serve the faithful? little different than "regularizing" with Protestants......for the majority of Catholics, so called in name, today are really, not Catholic.....not in theology, practice, etc...What makes you Catholic? it is what you belevie and practice!!!
The FSSP have no bishops, hence, are at the whim of the same liberal bishops that have wrecked and continue to wreck the Faith......not long ago, the FSSp was told, something called order 92 or something like it, that well, after 10 yrs, they were doing great, but, that Rome had never really said they did not ahve to be required to say the NO. So, said FSSP priest, who does he appeal to then? the local bishop? good luck with that one!!!! or Rome?? they are largly silent and indecisive...
The SSPX will not turn over their priests and flocks to Local Bishop Heretic....who would!!!