Well, Firstly, Naruto is probably a lot stronger then Sasuke. Their last match wasn't a win for Sasuke either, it was more of a tie. With the gaining of the Eternal Mangekyou it probably puts them at about even. It comes down to tactics and such in the end. Kyuubi VS Susano'o, Sasuke VS Naruto. The end result will probably be Naruto either proving to Sasuke how messed up his view of the world is and Friendship is Magic his way to make Sasuke a good guy again, or he's going to kill Sasuke. The fact of the matter is, Naruto will win, one way or another, some how some way, thats pretty much the -entire- premise of Naruto, much like Sonic, and Bleach. Somehow, someway, the hero will always win.