I've been sitting on it a while and I'm not sure if it's been said before, but, since Orochimaru is capable of "Soul Transfer" jutsu, couldn't Madara or Tobi have just taken Obito's body with the same sort of technique? Now I'm not sure how he could really live in a body that was half-way crushed, but it's just a thought. Kakashi is probably going to end up fighting Tobi and seeing him without his mask and lose the will to fight for a chapter or two. I honestly doubt Obito was ever Madara from the start, he always seemed to be more of a "klutz". Kind of how Naruto appeared in the first few episodes. Lol, maybe even Itachi needed a sacrifice to revive Madara and used his friend for it, thus gaining MS? I dunno, just throwing a few theories around.