Do you think the hokage's will head to the war ??

[Reidara]

Where I would normally not trust Orochimaru on his word, he seems somewhat content with helping Sasuke get his answers... probably because he resurrected him. (I'm not sure about the details haven't read the chapters before 599). I doubt, if Hashi managed to convince Sasuke to think otherwise, Orochimaru would double-cross the Hokage's and use them for himself, excluding Hashirama of course. Besides... Hashirama would not let him try that anyway.

I think Orochimaru is kind of in a bind and will do whatever the hokage want simply because Hashirma is no longer under his control.