@holden I have read it all before replying, but even before talking RSS (that I heavily use and in fact implement basic monitoring for clients using this widely available protocol) I want to reply about your idea :
Your idea to me sounds like a mix of Quora and a Wiki. I love the idea but I don't understand why or how it would imply RSS is dead. No seriously.. Something can be dead for your use of the Web and simultaneously completely alive for tons of other profiles and widely used even if without much bragging about it.
I'm not a coder, so I can't help develop your idea but I think in your idea an RSS implementation would allow me to subscribe to discussion, hell your idea could even integrate #indieweb from the get go and Allow the open web to answer and interact with it like I'm doing right now on my on site back to your tweet.
Behaviors change but open protocols only die when privatized (take Facebook Instant Articles, its basically RSS feed that publishers are providing) but even that is certainly not the end for RSS.
Open Protocols, Let's make them thrive!