1. Hashirama is still the "ultimate" shinobi. << There hasn't been a shinobi like him for a while. Naruto is slowly getting there, but he lacks the experience.
2. The dude was proficient in all ninja skills. fuijutsu/summonings/senjutsu/ninjutsu/genjutsu/taijutsu/kenjutsu
3. Not only simply proficient in them.. but also, POWERFUL in them.
Yea you can argue that Naruto/Sasuke are stronger than him.. however, that does not mean they are the "ultimate" shinobi yet. For one, they lack experience of war. And someone like Naruto also lacks pure training. << Something people like Hashirama/Madara/Tobirama have alot of.
But yea I don't see Hashirama being surpassed as the "ultimate" shinobi until Naruto becomes an adult.