I think HN will last more. There is a reason, HN is not a business like is Digg or Reddit, so I bet Paul Graham will try do to his best in order to take the site useful and don't attract noise here. The other sites can't do too much if the metric is "more garbage but much more pageviews", here instead there are no deals to do, nor ADS to serve, so the site can be adjusted just in order to maximize the quality over the time.
