If it is in fact Obito (which is being seriously implied with his sharingan, speech and other hints) Kishi is going to have a truckload of bull%^&* that he's going to have to pull out of his a$$ to explain such a radical change in behavior on Obito's part. As well as how he survived being crushed to death.
I reread the Kakashi Gaiden chapter and I'm pretty sure that he himself (Obito) said that "The left side of my body has been completely crushed, I can't even feel it anymore.". Furthermore, how would someone like Zetsu or Madara find Obito under that rubble and be able to restore his body and Sharingan to the point where it could be usebale.
After that being said, how the hell did on top of all this, become powerful enough to take on the Fourth?