As much as I'd like Sasuke to remain a "good guy", I'd have to say if he stayed with Orochimaru it would be a good thing in terms of developing the entire team 7. I think the idea of having a flash-forward if he gets to him is a good one. A couple years or so maybe.. :

With Sasuke gone, Naruto will no longer have a rival to compete with and motivate his training. Instead he'll use his devotion of becoming the next Hokage, a higher purpose (in my opinion) that will lead to better results and higher leaps in his training than just competing with another Genin. He won't forget about Sasuke but he won't obsess over it either, not for the whole flash period anyway (then again, being Naruto, he just might..).

Sakura will be crushed for a while at the loss of Sasuke (obviously) but eventually get talked around. One of two things could happen: She'll devote herself fully to training as a Ninja so one day she can go "rescue" Sasuke.. Or after she gets over the initial devistation, she'll become very angry at him and use THAT to fuel her training, and maybe one day go get revenge for him hurting her so bad. (Wouldn't that be ironic..? Revenge against someone who's life revolves around revenge..)

And obviously, learning and training with Orochimaru and Kabuto will probably strengthen Sasuke immensely. He'll learn how to use his seal probably better than the Sound Four did, and will most likely be taught countless Ninjutsus that Orochimaru knows.

But no, I don't think he's going back to Konoha (My vote).