...What's the point of this Thread? o_o
Anyways, if they get seperated (either because they are split up or Sora returns to Destiny Islands) then it happens. The point of all three of them being together was because King Mickey asked them to find the Keybearer to help him seal all the Worlds' Keyholes. When that is done, Kingdom Hearts is locked forever, and peace is restored then naturally they'd seperate. Their job is fulfilled. I suppose it'll be sad, but it may very well happen.