I don't understand why there has to be a bubble. For example, time passes in WoW just fine. Just have the game say that the ARR content takes place 5 years after the Calamity, Heavensward 6 years, Stormblood 7 years, etc etc. Players aren't stupid.

Edit: At some point "it's five years after the Calamity" is going to look pretty dumb, given all we've done and are going to do. They mention the Simpson as an example, but then I can't stand that show. :P