i think that since in the ending they show kairi running across the beach to show sora and riku a note from the king,maybe its another mission.and they where sent off to the graveyard to get the keyblades.but then that wouldnt explain the chasers..they did explain in the other games about the body,heart,and soul..but what happens to the soul when the body and heart are turned over.maybe it becomes like a chaser (a being ''chasing'' people for a body to claim ect.)also what about the story of the keyblade,im thinking that since in the story one keyblade ruler is to bring peace(sora) and one is to bring chaos..and they never had that takem care of in any of the games,maybe this game is going to be about the keyblader that brought ruin to the world.and maybe he went to the keyblade graveyard to recieve the keyblades used to save the world (because really soras story was over and so maybe the keyblades where sent there) and now sora and the others need to get the keyblades back and save the world from the ''anti keyblader''.maybe even the ''anti keyblader'' is a ''chaser'' of sora just as roxas was a nobody of sora..those are my theories like em or not