Most people already know that Sasuke and Naruto are going to fight, and believe their fight will resemble Madara vs Hashirama, but I disagree. I believe that it will be something like the Sage of six path's elder son vs the younger son, making the fight the ultimate body vs the ultimate eyes.

I will first go on to explain why Sasuke will be like the elder son and not like Madara. We do not know much about the elder son, but we know that he was full of hatred and believed the Uchiha was far greater in power than any other clan. This resembles Sasuke, Sasuke is full of hatred, wants revenge, and believes the Uchiha's are the greatest. Sasuke's hatred is so great that you can visually see it in his Susano'o, and when Karin was looking at him. Madara on the other hand isn't full of hatred, doesn't want revenge, and does not care much about the Uchiha clan. It is proven through what we have seen that all Madara is interested in is watching an exciting fight, he was defeated by Hashirama, and instead of wanting revenge; he respects him, he left the Uchiha clan as well as used Senju DNA which means he is only in will of power and not of being a true uchiha. Also, just as an extra resemblance, they both are skilled at using a sword.

Sasuke is an extremely proud Uchiha, and if he were to take any Senju DNA and obtain the rinnegan, he would be a hypocrite. He is so in love with his clan, that his whole life is derived by will to restoring his former clan and revenge on his brother (now destroying Konoha for his brother). That's why he wil not get the rinnegan, but probably the same dojutsu the elder son had, which looks like a rinnegan, but is twirled in.
This is most likely what Sasuke will obtain once he gets screen time and goes to the Uchiha ancestrial monument with Orochimaru.

For Naruto he is also a lot like the Younger son, because they both know that love is the key to peace. They are alike in several ways, one being that people put their trust in them. Just like Naruto with all the people who have put their trust in Naruto (8 bijuu's and most Konoha Shinobi) the SO6P put his trust into the younger son. The Younger son is said to have great life force and physical energy, something Naruto represents greatly as well (he made Yamato's wood style grow tree like when he was near it. The younger son may even be a jinchuriki just like Naruto, as he clearly has a powerful body to with hold it. His will is supposed to be the will of fire, and Hashi supposedly has this will from him, and Naruto does now to.
in this picture you can see the younger son is enveloped with some sort of cloak,representing the BM or KCM cloak greatly, meaning he may have been the 9 tails jinchuriki back then. There also may be some minor possibility that this is an image of a SM although I doubt it and believe it's a KCM.