Board Thread:Naruto Discussions/@comment-5054236-20150717003436/@comment-5273810-20150717020130

WindStar7125 wrote: 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. @Windy when Kabuto saved Sasuke's life he gave Hashirama(Asura Transmigrant) DNA, getting a dose of So6P power just hastned its awakening from decades to instant.