Of course there are always dimensions where things still happen despite what Elizabeth said unless she gained god like powers over the multiverse. It was my understanding that she could perceive all possibilities, but does that mean she exists as a single mind across every possible variation? The ending suggests she isn't a single being across every dimension.
There will always be a reality where things don't go according to Elizabeth unless the fiction sets up a "Columbia Prime" that is the true version, but that usually pops up in time travel stories and not alternate dimension stories.
It's implied that dimensions only diverge at key junction points, meaning that the number of realities with Comstock and Columbia may be large, but no infinite. We see throughout the game how actions in one dimension can impact denizens of other dimensions with the soldiers that remember dying because you killed them before travelling through the rift. It is therefore conceivable that by killing Booker at that crucial junction point in one dimension, the same effect echoed out to the other dimensions preventing any Booker from ever going through with the baptism and being reborn as Comstock.