As someone whose been on "both sides," I did not believe that someone like "Pope" Francis was even a possibility. "Bad teaching," yes; "public heresy," no. That latter possibility, I believed, would be forever excluded by the Third Person of the Blessed Trinity.
Well, I was wrong, not the Catholic Faith (which is absolutely perfect and immutable), of course, but my private understanding of it. As for "dogmatic sedevacantism," I think that everyone here has their (your) limits. When "Pope" Francis starts denying the Bodily Resurrection of our Lord Jesus Christ and/or diminishes Him to no more than a "pastor and teacher" or our Lady's Assumption to that of "allegory," I think that more of you will cross the Sedehold of Hope.