I agree that it's a mistake for most sites to have a forum as some ill-conceived appendage (I once exclaimed to a friend that "forums are favelas!" on most sites), but think interest-based communities have a bright future.
We'll have this really figured out when I open a news story in my browser and a second window pops up on my other monitor with a list of comments linked to that article from Twitter, Facebook, G+, HN, Reddit, Digg, or whatever social sites or aggregators I'm into.
EDIT: brevity.
My country's biggest online newspaper recently switched to full-name only comments, which is a dealbreaker for me. It would be great to have an alternative community which isn't subject to each news source's arbitrary moderation policies. I have seen outright censorship many times, and it doesn't feel right to contribute to an online discussion where certain views are removed from consideration. In fact, I feel that the full-name policy is a flawed online discussion strategy, and this would be a good way to solve it.