Hrm, a reoccuring theme throughout the series seems to be Naruto redeeming souls. First the little boy in the first Arc, and Zabuza. Then the next one was Gaara.

While it would be interesting to see Naruto fail in this instance, it would really break up a pattern in the anime.

I'm hoping the writing comes up with something creative as far as how the redemption of Sasuke occurs, but who knows.

I really can't see sasuke becoming a villain at this time due to the roll of evil sharingan user being filled by itachi.