IRC as a concept has never been healthier. Lots of alternatives, most proprietary, some libre, and more users than ever.
I'm not trying to be difficult, I have used IRC since the 90s and still use it. It's just the best format for chat imo.
But my observation is also that it's dying slowly.
Is it? I'm not on it every day, but I don't really notice a change. Isn't it just that it isn't growing, at least not as much as the explosions of web-based, proprietary platforms like twitter or slack?
Me and my little group of hackers would also host our own, and link with other groups around the world.
I think it boils down to accessibility. Even back when I started certain people just couldn't handle the terminal clients so they used Xchat or Mirc. In school in Sweden IRC was actually often pronounced "mirck" because people would refer to the mirc client.
So when web chat came along, with mobile apps too, it just reaches a much wider audience.
So the ones who are left on IRC are old farts, and terminal junkies.
In 2004, top 10 networks had together around one million of users. now, it's around 150 000.
Top reason of this decline is gamers leaving the network. Quakenet and GameSurge had like 300K users together, now less than 10K (and probably mostly bots or bouncers).