Sasuke definetly wont come back now even if he loses to Naruto because it would be pointless for him to be brought back by force. He needs first to see that we he desires is wrong. Naruto whooping his ass wouldnt make him come back because Sasuke would just become angrier at him. The only for Sasuke to come back is for him to come back willingly. This will only happen if someone he cares about is about to die or something and then he realizes the errors of his ways and saves them. He left because he convinced himself that his friends dont matter, so he needs it proven to himself that he cares in order for him to ever be able to come back. I really think that he never will come back and instead will just turn good again just in time to die to save someone else.