I don’t see why films about the Sith Empire or the Mandolorian Wars would need to take the place of the PT though. Those could easily exist without splitting the continuity. I just feel like the last thing Disney wants to do is complicate the timeline. They’re all about bringing in new fans right now, and introducing alternate continuities would be a bad move for that. Better to just build around the prequels and reference them as little as possible.
I can’t remember if it was here or the AV Club, but at some point I heard someone say that their personal canon was that the prequels are factually accurate, but that the films themselves as we know them are essentially in-universe B-movies of the actual events that took place. That’s pretty much the attitude I’ve adopted since reading that, and I’m fine with sticking with it.
Like I said, series reboot all the time now! If people can keep track of all the superhero universes (there’s at least 10 film universes based on Marvel heroes and that’s not even counting DC), they can keep track of two Star Wars universes (three if you count Legends but that’s pretty obscure now).