RSS 2.0 already does comments in feeds. I think that syndication (RSS , Atom, etc.) will be bigger than blogs but without blogs RSS wouldn't be where it is today.
So, this means that the smart money is going to go into the feed space. Because that’s where the action is. Forget AdSense. I need contextual ads built right into my feed. Forget Typepad links, I need the links built right into my feed. Same with comments. And the feed needs to be two way. Atom has that capability I am told. So let me comment right in the feed. That’s a hell of lot better than Trackback.