alt Hacker NewsThere is a lot of interesting work in this space by the IndieWeb community. They've got a vision of (and lots of a spec for) a social reader[1] that uses RSS for lots of the things people got in the habit of with Web2 social media (comment, repost, etc)
(Although the IndieWeb community has this weird thing against "side files" and prefer having the content inside the HTML, marked up with Microformats2 special attributes. A social reader then polls the HTML and parses it additionally with the Microformats2 algorithm. I suspect this cultural preference is a result of the usage of static site builders of the early IndieWeb pioneers like Tantek.)