I don't think Orochimaru will joint the fight, at least when both sides are still "healthy", he is a smart demon after all. With Orochimaru Edo Tensei, I don't think it will be possible for the Hokages to break it easily.
There will be a way Sasuke get the Rinnegan and read all the script on the stone? It hasn't been fully read, isn't it?
Naruto and Sasuke fight unavoidable unless one of them die before that happens. But I think it will be in the far future
