I've had this conversation a few times in the week or so. Usenet still exists, but to what extent I have no idea. It might be worth to try out Giganews or any number of other providers.
As a discussion system, it's pretty much defunct at this point.
It's pretty much fine as a discussion forum.
Things have been lively in comp.lang.c recently with a little coding exercise going on and such.
comp.unix.programmer and comp.unix.shell are active also.
comp.theory has been quite active due to a crackpot who insists that he has solved the halting problem, or at least refuted common halting proofs using a nested x86 simulator that detects recursion, haha.