He is not overrated just talked about most often mostly to shut up fan boys of SPECIFIC Characters. However... It was said Rikudo sannin was stronger than the Jubi, overpowered it and defeated it becoming the first Jin, and Jin of 10 tails.
Let's just speculate, Naruto the 9tails Jin. How strong he is just being a 9 tails jin, and it's not even the full 9 tail chakra. Than... Add let's add the rest of 9 tails chakra plus the other 8, added it together, and multiply it by atleast 2x if not more than you have the Rikudo Sannin's Chakra reserve.
who can beat someone with chakra level 2x Jubi. I only say this because he has more chakra than jubi, plus the jubi in him.
I would like to see someone beat that. but again not possible because he is dead.
I do think someone will surpass him.
Y Make someone so powerful and unsurpassable, yet that specific person didn't fix and change the Narutoverse and establish peace. That is my reasoning why He will be surpassed, because someone has to embody him, but more improved.
However, if I start seeing other ninjas somehow mysteriously transferring chakra to someone. Like how Goku collected spirits for the spirit bomb. I will defintely immediately stop reading/watching Naruto.