They'd likely both die like Indra and Ashura. If not then Naruto likely kills him like Hashirama did Madara. Depending on whether or not Sasuke does the izanagi trick too, he'll come back and the cycle continues like with Madara.
But honestly I'm glad Naruto didn't fight him all out like that. Plot and story aside, I think it would've been a much better fight if SASUKE took it down a notch. Wanting to kill him so bad is probably why he didn't get his way, same for Indra and Madara. But then again that was the only way he was going to do what he wanted so I can dig it