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.

From observing Sasuke and Madara, Naruto not getting the Rinnegan could be because he lacks the Sharingan. But then again, there's no confirmation of Hagoromo having the Sharingan either (though possible). It's another thing Kishi decides to keep unanswered.