I don't know if Sasuke would just challenge Orochimaru out of the blue...it seems like he'll win this fight!
Then again, where's the justice in Orochimaru being killed by Sasuke and NOT one of the three Sannin or Naruto? I guess that goes back a chapter or two, to when Kakashi says that "the new generation will surpass the last."
As far as Naruto VS Sasuke goes, the next chapter or two after this battle will probably relate to more Naruto training, so that he can really defeat Sasuke, and drive him back to Konoha's camp. That way, Itachi and the Akatsuke leader will be the main focus.