Naruto doen't need the sharingan to fight with Sasuke, or to counter Sasuke's speed. Naruto has sage mode, and it's speed and power will only surprise Sasuke once. Don't forget, Sasuke is extremely smart, and Naruto is not. Neither of them knows what skills the other posesses, and when it happens, it will be a long great fight.
So far, I don't think that Naruto would kill Sasuske, even though he knows that he will have to (Spoiler alert: in the manga - refer to Kakashi's and Naruto's conversation before Naruto and Sasuke fought for a moment, after Sasuke killed Danzo).
But if Madara interrupts, then Sasuke may kill Madara, which would give Naruto a better chance after Sasuke's chakra is depleted from battling/killing Madara.
Pein or Madara are the only ones that have been mentioned (so far) to know of the Sage of the Six Paths. Who would teach Naruto those skills? -> that would be his best chance to become the Child of Prophecy that Jiraiya and the toads believe Naruto to be, and for Naruto to fulfill Jiraiya's dream of people understanding each other, and breaking the cycle of hatred in the ninja world.