I don't think that's the real hurdle for scaling up. The issue for large-scale democracy has always been that, because an individual's time is limited, it's very hard for them to make a reasonable appraisal of everyone else's opinion. If these comment threads were merely thousands of posts long, could you read through more than one of them and still have a life? And that's only thousands; the voting population of the US is a bit over 200 million.

I'm really, really looking for the tool that lets you successfully absorb thousands of opinions around an issue within a reasonable time frame, without intermediaries. That's the killer app for democracy.