Well Tobi seems to have shown an interest in Sasuke but the why?

In chapter 573 Tobi says " Naruto is merely a pawn to be used to stimulate Sasuke". This leads me to believe that Sasuke possesses something that Tobi wants or needs to complete his moon eye plan.

Alot of people have been saying that Sasuke will activate the rinnegan while fighting Naruto, I think that while fighting Naruto Sasuke will activate something more powerful that the sage of six paths had which is basically the rinnegan and the sharingan mixed together in the same eye.

This is just a theory so feel free to tell me what you think