I think people would collectivize into communities with agreed upon rules without everyone in the world signing the same contract. You could find a place where you agree with the rules. I don't think there will ever be a total lack of rules.
I think the reason that Socrates stated for serving his sentence was that he believed in the social contract. That is where he was dead wrong. Socrates was an amazing mind, but if he truly believed in a social contract, he proves that he was only human. Maybe that was his final lesson to the world? It sure did stick.