Board Thread:Naruto Discussions/@comment-24826628-20141011195726/@comment-3279282-20141013013724

Naruto's new powers after his death were 1) the seal, 2) the Truth-Seeking Balls and 3) the Six Paths Senjutsu. After he sealed Kaguya, only one of those things returned to Hagoromo: the seal. This means it's highly likely that the other two things came from another source than Hagoromo. The only other possible source are the missing Tailed Beasts which Naruto got from Obito.

The same goes for Sasuke. He got 1) the seal and 2) the Rinnegan. Only the seal returned to Hagoromo, which makes it highly likely that the Rinnegan had nothing to do with meeting Hagoromo. The only other possible source is Kabuto's doctoring with Hashirama's cells. This actually matches what we know about the awakening of the Rinnegan: Uchiha/Indra and Senju/Asura together awaken the Rinnegan.