Sasuke getting the Rinnegan and the Sharingan makes total sense. Tobi needed someone with the Rinnegan in order to synch with Gedo Mezo.
Sasuke doesn't care if he's being manipulated. He just wants the power to destroy Konoha. Though, I wonder if he's going to try to pull the same thing that he did with Orochimaru. I bet Tobi will have an ace up his sleeve in case Sasuke gets out of control.
Naruto has always been about coming out on top against all odds. We want Sasuke to get overpowered. You know why? Because when Naruto finally hands his ass to him, its going to be even more awesome. :flaw: