Spoiler ShowSimply, I know how everything can fit into one game.
We have several storylines.
Riku and Kairi are looking for Sora in a dream world.
Storyline with Subject X, as well as the search for Sora through the memories of Roxas and Xion, TAV in the realm of darkness, as well as MDG in the Disney worlds.
Verum Rex, under which they will probably single out a separate game.
At least three more games are needed.