What would really happen is this:
I've been studying those stupid bills. Say your site was legit and had no one else's copyrighted stuff on it but yours. Say someone at Columbia Pictures, government, or someone you pissed off, viewed your site and didn't like what you had, saw it as some type of threat to them, or just simply didn't like something you said on the site. They would just file a complaint, and your site would be erased instantly. No proof needed. No warning, no nothing. And worse, you have absolutely NO recourse. So basically you're just screwed. But there's nothing in those bills that says you can't do it back to them. (of course if everyone did this to everyone, we would have an internet with nothing on it.)
Also, for sites that manage to stay in existence, they would be heavily censored. So if you're talking to someone about Occupy Wall Street, it will most likely be changed into something else by the time it reaches the party you sent it to. Remember how Yahoo recently censored emails? (and they're still doing it) Just like that.