I personally believe that Sasuke is becoming another Itachi. He's saying what Madara wants to hear, and is actually going to attack Konoha, only to provoke Naruto into doing... something. I still don't know what Sasuke's true ambitions are at this point, but it's painstakingly clear it's not what he's saying.

I hate Sasuke, but seriously. His character could not have sunken that low.