Silk Road is a good example of what will happen. Some media mogul will eventually cajole the government into acting. The government will go to the NSA, find the true identities of those responsible, then cook up nonsense about how they gave away their identities due to some weird Stack Overflow question no one could ever notice. The US Attorney will prosecute, and claim that it's a felony because of economic benefit, even if no money was exchanged. The culprits will end up in supermax. They can't afford to do this to everyone, obviously, but they'll pick up to 100 or so of a mix of the worst offenders and the most casual users, to "set an example". The media will publicize it to the point of absurdity so the message sinks in.