A collapse, as a disappearance of orthodox Latin Christianity seems really implausible (and coming out of nowhere).
Even a greater schism (that is obviously a political, not a religious issue) would lead to a divided Catholicism, not its collapse : depsite a political collapse for Byzantium, Greek Christianity didn't collapsed.
It's simply too well rooted into the population : at their best the heresies quoted by Velasco didn't reached 2 to 5% of the population in some aeras, generally far less. The exemple of Protestantism could be admittedly contradictory, but a more expanded alt-Reformation is going to replace de facto Catholicism, not making it collapse.