As the manga has said before, Sasuke's curse seal is levels above the Sound 4, on par with Kimimaro. AND if Kimimaro in level 2 nearly killed Gaara, we might imagine what Sasuke at level 2 would be like. Perhaps not so godlike, but still with a capability of taking down uber-Kyuubified Naruto. In the end I believe they'll knock each other out, then I think there's gonna be interference, but I'm thinking it would be Kabuto coming out after Orochimaru gets waaaay too tired of waiting. Then we get our Kakashi vs. Kabuto, where neither of them can afford to run away if they want to accomplish their misisions. Where we can finally see who's more badass