he hasn`t come back yet.

im pretty sure he kills itachi and takes his place on the akutski

One of my friends in the Phillipines told me that Sasuke basically goes nuts and tries to destroy Konoha because of the elders and danzou ordering Itachi to kill their clan. He also told me that Naruto had to kill him with some kind of ice/crystal rasenshuriken, so I don't know if he comes back but if he does it's to destroy Konoha.