I'd love to see irc florish.
I've seen the following noted by others as well: end-to-end encryption doesn't make much sense for public chatrooms, so proper transport security guarantees and modern feature set goes a long way. IRCv3 has some nice things. Some people seem to want persistence but I thought it kinda nice to just go in and go with the flow. Maybe some identity that allows one to find another easily. That's the one thing that would make personal interaction more convenient.