I still fuck around with IRC from time to time but it definitely has fallen off heavily in the last 5-10 years. Usenet does have its pockets of activity but it's definitely more of an older generational thing. Misc.survival and comp.misc were two places that at least last I checked had some decent activity if that's your thing. Most of Usenet is definitely a wasteland though, made harder to navigate because some of the groups still just get flooded with bots and literally nothing else.

Also spent a bit of time on the BBS message networks such ad Dovenet and Fidonet. Similarly older crowd. The charm of ANSI art on BBS's is something I'll always appreciate.