Sasuke mightn't even get Rinnegan yet... Kabuto said: "Yes... With my Medical Ninjutsu, the cells of Hashirama I've studied so far..." Which could be interpreted in a number of ways. (A) He is indeed using Hashirama's cells to heal Sasuke. (B) He has improved his Medical Ninjutsu to another level by studying Hashirama's cells. He could be pumping Juugo's cells into Sasuke, or even transfering Senjutsu Chakra in hopes of helping him heal.
The fact that i think that the Rinnegan is only obtained by Senju+Uchiha+Juubi's Chakra makes Sasuke ineligible for Rinnegan. Both accounts of people obtaining Rinnegan (Hagoromo and Madara) had three things in common. They both had Senju+Uchiha DNA but people seem to forget that they had Juubi's Chakra. How?
When Kaguya Otsutsuki ate the Juubi's fruit she gained some god-like power's. Chakra. Her powers which would've included some of Juubi's Chakra from the consumption of the fruit were passed onto Hagoromo. (Some of Juubi's Chakra) thus he had Senju+Uchiha+Juubi's Chakra.
For Madara he implanted Hashirama's DNA sometime after VOTE. He was also connected to the Gedo Mazo for a prolonged period of time, essentially the Gedo Mazo's (Juubi's Body which would of had remnants of it's Chakra) Chakra would've been integrated into Madara. Thus unlocking Rinnegan. It would make sense that you need Juubi's chakra as well seeing as the Rinnegan is so similar to the Juubi's eye.
This is all just a theory though, Sasuke could in fact unlock Rinnegan, we won't know until we see.
