Jeni's Musings

Yes, it could certainly work like that. As long as flickr (or whoever) made those feeds available to the wider web, there is hardly any difference between new comment resources being hosted on your own site and them being hosted on a separate site.

So in the Atom Threading Extensions, you can either point from a resource to a comment feed with replies or point from a comment to the resource with in-reply-to. The only difference between the two is that it’s slightly harder to identify all the comments on a resource if they’re distributed, but that’s precisely what brokers are for.