I think there are still plenty of discussions about high-end gear. Look how many threads on K1000s have cropped up recently, either in the amp section or, for comparison sake (e.g., with K701s), in the headphone section. I haven't been around long enough to note forum shifts, I have found lively, lengthy discussions and useful information in meet impressions threads, which I frequent as much or more than other forums. Take a look at the recent K1000 meet in S.F., or even the Dec (or was it Jan?) FL meet, which branched off into an electrostatic amp discussion. The cables/tweaks forum is also useful, but sometimes suffers from posters who just don't want to let those who choose to explore this area do so.
That being said, I have been fortunate enough to acquire some higher-end gear this past year and have lots of questions. I have never started a thread with these questions, but have had wonderful email correspondence and phone conversations with more knowledgeable members. So maybe I'm part of the problem (if there is, in fact, a problem). I'd rather do a profile search and ask specific members for advice. It's efficient. I don't have to wonder if the one person who may have an answer can find the thread, and I get my questions answered without all the extras some threads bring.
At any rate, information is still available if you have any question re high-end gear. If you're interested enough, you'll find it, and knowledgeable members have been more than gracious in helping.