I had learned that in Catholic Doctrine class in college 30 years ago, so it wasn’t news to me. Nice to see it reiterated by someone who knows what he is talking about and has some authority.
There are those that believe the SSPX is in schism and those that believe it is not. There are those in the SSPX who believe the current dialog with Rome is a good thing and those that believe it is a betrayal of its founder. Even outside the SSPX there are conservatives on opposing sides of the Vatican II question. For example, the family split between those still with The Wanderer and those that became The Remnant.
The one thing all of these factions seem to agree on is that ecumenism is a dirty word and so any hope that they will all come together under a common understanding seems futile.
‘It may be possible for the SSPX to be fully integrated.’
Of course. SSPX think they are so special. SSPX have issues that can only be solved by humility and obedience, just as for every one else.