The genius of satoshi was in the cryptographic field, and most importantly, having the vision to put all the (already existing) pieces to form a new thing. PoW was already there, distributed networks with nodes were already there, he just made a pack and it worked. The code was rough, apparently it lacked a lot of fine tuning, but that's not important when the concept is genius and it actually works in practice.

This is why someone that is a better coder could come up with another cryptocurrency, but if it's not a game changer at the scale of what Bitcoin was in 2009 (and still is) then it's not going to get anywhere, the network effect is too strong in Bitcoin.

Whoever wants to challenge Bitcoin must come up with with a completely new way to solve the Byzantine General's problem and do it in a much more efficient way, which I doubt it's going to happen for at least 100 years which is what these big problems usually take for someone to come up with new solutions.