I believe that YNews is supposed to be a place to quickly catch up on the latest thoughts in the start-up community. It should serve the interests of the busy start-uper and minimize the amount of time needed to get informed -- a chat room does not do this.
Additionally, chat room discussions are disorganized and difficult to properly archive. They represent a step back from threaded discussions; however, chat rooms offer real-time communication. That's their sole advantage.
I think if that's what we as a community want, we should propose some features to accomplish those goals without losing the advantages of threaded, archived discussion. How about features like thread subscriptions, reply alerts, the ability to reply to a child comment via text message, thread organization tools (some distinction between link threads and discussion threads), etc... There's no need to cannibalize the existing community system when better alternatives exist.