Man, part of Orchimaru was hit with Itachi's Totsuka sword, but a tiny piece of him, escaped, the LITTLE white snake, which has his essence, but it was burned by amaterasu..... BUT then again, Kabuto has implanted Orchimaru's cells in himself... But and I quote, Kakashi or whoever was with Naruto's gang when they met up with kabuto sometime after Orochimaru was "killed". He had some features of Orchimaru on him, and Kakashi said himself, that Orchimaru was slowly taking over Kabuto's body. Don't believe me people? Of course you don't believe me, but watch the episode where Kabuto hands Naruto that little book before he vanishes away... Kakashi said that Orochimaru is slowly taking over his body.... NOW look at Kabuto.. He's looking more and more like Orochimaru. It's going to be a matter of time, before the Sannin returns... And in my opinion I do think he's coming back, because honestly, he's one of the main villains of Konoha, while Tobi is the ultimate villian of the entire story.