I really don't know...
Mokuton is a truly OP ninjutsu and even if Naruto gains his other half, a Yin/Yang BSM Naruto still isn't beating Hashirama. I don't see Naruto getting the Rinnegan either because he definitely isn't getting any Uchiha's eyes.
Only way I see him surpassing Hashirama is becoming the Juubi's jinchuuriki, and I doubt that happening too since he wouldn't ditch a friend such as Kurama for a mindless god. Also, Naruto's lived with Kurama since birth, I don't think anyone else has experienced that except from Gaara (can't remember when he became Shukaku's jinchuuriki; either at a young age or at birth) and due to this, I don't think Kurama is gonna be extracted and become a part of the Juubi. I don't even think Kurama can be extracted since the Juubi is in it's final form and it definitely isn't necessary extracting him.