I don't think the same thing can't happen here at all. I agree with you that if they really wanted to pursue that path, the human cost could be enormous. However, we're also saying that if you really wanted some weed, there remain many avenues available to you to acquire it, despite all that will.
Trading movies and music online is a lot different than using or trading an illegal drug. People actually will stop downloading movies, etc, if it means going to prison. It is pretty easy to stop yourself from watching movies. It is not so easy to stop your physical addiction to a drug. The risk/benefit in the mind of a copyright infringer is on a completely different scale than the risk/benefit that exist in the mind of a drug addict.
I'd bet that the belief of likelihood of prosecution for a drug crime is about the same as being sued by the RIAA or MPAA for most people. They're aware they could get in trouble, but it's unevenly enforced and unlikely to actually happen to them.
Regardless, I don't think the willful infringers are the most interesting group here. If user generated content really does lead to sites getting shut down in an unreasonable way (which is probably unlikely to actually happen), I think it's those groups that would be leading the charge to a next gen network, not the infringers.
