Even if there is no bitcoin, at some point someone will think about the very same idea. If Satoshi was able to think about it, so can the other people that share the same field of interest with Satoshi. There's newer and newer concepts popping up and someone that has knowledge in both the economy and cryptography will eventually think about starting a revolution. Although possibly it will be decades from now before someone ever thinks about this very same idea. That's why you'll someday stumble upon an article that's has a theory that Satoshi came from the future, and left us behind with the bitcoin idea (to save from what the future monetary system holds).