Something with DNA, the Rinnegan's Genetic Code is still in there, for both the Senju and Uchiha. It all depends if its dominant and recessive genes. The sharingan was a mutation. I still believe Naruto can some how awaken it, if he's pushed enough. When the Senju and Uchiha DNA combine, the Rinnegan became a dominant gene again and awaken. Naruto still has a chance to awaken it on his own, or with a help from a Uchiha. I feel like Naruto best chance to awaken it is, through getting all the chakra from Kurama. Since the tailed beast, have effects on the person they are sealed in, Look at Naruto whiskers, that suggest that Kurama's chakra influenced part of Naruto's DNA, who know's what happens if he gets all of Kurama's Chakra, it would be flowing more, and might cause some effects to Naruto.