I'm guessing Kishi will have Naruto either not use Kurama (aside from the chakra he already gets by having him in the first place), have him not be ABLE to, or have Kurama refuse because it's Naruto's fight, and not his. This is the only way I see it being even...although no one really knows how much more we have left to go before they fight, or even IF they will fight at all. (A lot of people are gonna be MAAAAD if they don't though, lol)
I am not sure if Naruto can use Kurama against Sasuke, because Sasuke can suppress the 9T chakra, as we saw when they met at Orochimaru's lair - and that was with a regular sharingan - wonder what MS could do.
Also Naruto stands at a distinct disadvantage because he wants to save Sasuke, not to kill him, whereas Sasuke wants to kill - far easier than save... Almost all of Naruto's techniques (other than shadow clones) are killing techniques. He is not going to use TBB or RS against Sasuke because he does not want him dead (except if it's the only way to save others).
Sasuke also has genjutsu, which I doubt Naruto can easily counter (even with Kurama's help), and amaterasu, which nearly defeated Killerbee.
This is by no means a walk in the park.