All that said, my biggest concerns would be that it's a huge chicken-and-egg problem, plus the difficulty of getting users to pay for content they're used to getting for free.
Oh, and you come across sounding like a real asshole.
I make a point not to spend time around the pessimistic downer crowd, and it ticks me off when someone shoots down an idea offhandedly. I sincerely hope HN does not move in this direction.
Did you miss my post where I said it was a bad attempt at humor? Shame on you for trying to make me personally feel bad.
Shame on you for thinking that disparaging people is valid revenge for people who merely poke fun at ideas. Talk about making it personal.
There are a number of ways that you could have phrased your response that would have stimulated real discussion instead of "har har lolz anti-spam newbz"
I don't even have to look at this new scheme to know it won't work. It won't work because it relies on a critical mass, and until it gets that critical mass sites won't switch, and until they do users won't sign up, so there's no critical mass .. your classic chicken and egg problem. No-one is going to pay unless everyone else has to pay. There is nothing to force everyone to move at once. See: history of "penny stamp" email anti-spam ideas.
The form style helps ram these notions home; it's a welcome reality check in situations like these.
(updated to stay on topic)