I'd say it's normal for a thread to die out after all those who wish to respond have discussed it. Sometimes an old thread is resurrected by a new member, and then there may be a few more responses before it fades out again.
By far the biggest change on here is the lack of posts, and responses to posts, in the forums other than Political, PBS, Today's news, etc. Almost no discussion on guns, hunting, fishing, etc.
It's really striking on the H&R forum. Used to be at least a page or more of posts there every day, now maybe just 2 or 3 threads.
It's happening all over not just here. On H&K and 1919a4. How many times can you talk about either?
GBO has diversity, it will and has survived.