I dont think Id like sasuke to get rinnegan for one simple reason.. its been done. Both obito and madara have the sharingan/rinnegan combo, I think I'd prefer to see Sasuke become stronger in a more original way. And why does sasuke need to master all 5 chakra natures. He already has lightining and fire, susanoo, and the unlimited powers of the sharingan.
Im not saying its impossible or that sasuke doesnt have a good power up coming his way to keep competitive with naruto. Im just saying that I have higher expectations