I believe Naruto can surpass Hashirama without Kurama. Remember Kurama made it harder for Naruto to use his powers/chakra, yet he was still able to learn jutsu like the FRS and Sage mode. So without Kurama Naruto would be able to use his powers/chakra to the fullest.
He has the potential to learn high level sealing jutsu including his mother's chakra chain seal. He could manipulate and use the 9 tails seal. If his mother's around she could show him how to use the Uzumaki clan powerful life force.
He has the potential to learn his father S/T. Naruto learned his own S/T during his sage mode training.
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This jutsu is in the 4th databook I just need someone to translate it to know exactly how it works.
Naruto can surpass KCM speed level with Sage mode and the body flicker jutsu combined.
Naruto still hasn't fully mastered Sage Mode. He showed us he has to potential to gather natural energy and activate SM while moving.
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