I can't speak for anyone else, but my personal IRC experience has simply gotten more private since the 90's. I still have an IRC client open whenever I'm on my computer, but these days I chat almost exclusively on private IRC channels and servers with people I've known for years. Instead of hordes of people swarming into large, public channels, it's a more intimate -- but just as genuine -- experience.

Still, though, that model seems unsustainable: fewer and fewer people are joining IRC channels or getting into what used to be a "scene." I think there will always be die-hards on IRC, but there's no longer the coolness that there was fifteen years ago.