Okay, so here's what I think:


The game could work if you the player were a real person in our world, dreaming about all the different FF games. Each zone would be one of the different FF games. Different areas of the zones reflect different points in the timeline of the game(zone) you're currently in. One zone would be for like levels 1-10, another game would be 11-20, etc. Each zone would have an instance/raid that would allow you to party up and fight the bosses from the respective game. A "hard mode" would exist for all raids that would allow max level characters to party and kill again, but the fight would be different. You'd start out as one class, but every time you change zones you have to change to one of whatever classes exist in the game you're currently playing in. The thing that would keep people playing the game after all the zones/games and killing the hard mode bosses would be PVP and extra open world "events" that would happen, which could be explained as "Some other dream is trying to invade your current dream" or something like that.


Lots of extra thought would have to be put into it to make it a viable option, but the only question that matters is, how many people would play it? I doubt very many people would do that, tbh, and since not many people would play it, it won't be made. Making a game is a huge money sink if you already foresee it failing.