I seem to notice that equipment in the "hifi" world that sounds good, tends to stick around for a long time. Vinyl records with the right combo of equipment sounds good, and fill that niche for carrying on the torch of nostalgia. Tube amps survived solid state amps, hence they are still around, and again, the nostalgia of tubed equipment lives on. Class A amps, they sound good, and just like record spinners, and tube amps, they have their foibles but most importantly, it sounds good. A few decades ago, I bought a pair of Nelson Pass's Aleph 1.2 Mono Class A bruisers; still have them, and they sound wonderful to this day.
In short, if it sounds good, and Class A amps check that box, then it will have longevity in the market. The designs will get better, the transistors plus transformers will get better, the caps will get better, hence technology will help keep Class A alive.
