I don't really get "local apps with sync". Sync to what, each other? In most cases there needs to be an always-on central authority (where backup also happens). My point is that "some device sitting alone in a corner with software and data stored on it" model is outdated (this is the "problem", I hope the "why" is obvious). But "local" should live on, just in the form of users owning most of their infrastructure.