Sedevacantists in Latin literally means, Pull up a chair and vacate your mind.
Several sedes have been kind enough to visit this crummy blog, read it, and make some comments and since that time, ABS has had a memory cell fired and so he desires to link to an estimable Blog which, justly, has earned a worthy reputation for orthodoxy and forthrightness.
This well--researched and well-written (Boniface is boringly adept at these things) post deals with the topic many sedes are, rightly, interested in; What if the dang Pope is a heretic or, worse, a registered democrat?
Well, check out the history of this Pope. If the act he likely engaged in did not cause him to be automatically deposed then Pope Francis has noting to worry about, short of becoming a ballerina.
http://www.unamsanctamcatholicam.com/apologetics/94-contra-sedevacantism/520-apostasy-of-pope-marcellinus-sedevacantism.html