Now if only we could find some way to incorporate every character from every previous FF. I mean, there's obviously a recurring theme. Protect the crystals and/or save the world. So maybe they're all similar universes in a specific "section" of the FF multiverse. And then one day a being powerful enough to threaten the existence of the very universe appears, and his power causes all of the previous FF universe to converge and everyone ends up in the same universe with all the enemies and superbosses from the previous games revived. Then you could play as any character from any of the games and fight all the monsters from every game.
...Except that all the people and monsters turn out to be the same person. And once they realize this, they all band together and find some way to use all the crystals to combine their souls (which are all the same soul from different times) into one super-ethereal being or some trout and fight the powerful guy and save all the universes. It would be the final Final Fantasy. The Final Fantasy. And then the guy that they beat turned out to be the dark version of the same super-ethereal being that they became when they combined, from a separate multiverse. And the whole storyline converges on itself and implodes from their manipulation of the space-time continuum.

...

Lol I'm so smurfing drunk.