Board Thread:Naruto Discussions/@comment-5054236-20150717003436/@comment-4271790-20150717012847

Well, Sasuke didn't get Asura's chakra and got the Rinnegan anyway. To my knowledge, the process is Asura + Indra's chakra => Hagoromo's chakra => Rinnegan. Or in Sasuke's case, just Hagoromo's chakra.

It's another thing Kishi decides to keep unanswered. From observing Sasuke and Madara, Naruto not getting the Rinnegan could be because he lacks the Sharingan.