Instead of human tailed beast power up, what if Naruto had an Avatar State like Aang? Instead of fusing with Jura, he taps into the chakra and powers of all his past reincarnations
Asura’s raw vitality
Hashirama’s Sage Body & Wood Release
Hagoromo’s blessing and divine balance
He becomes the Avatar of Shinobi History, guided by every soul before him. Sasuke, as Indra’s reincarnate, would balance him, as usual, Sun & Moon.