Or, there are endless discussions among the same few about minute and obscure details that almost no one cares about.
A quick sort of the forum by "Replies" reveals over 14 pages worth of topics that have received 50+ replies. I think this reveals a strong level of engagement beyond "the same few", after discounting the multiple contributions by this group.
I don't see postings by "the same few" as a negative in any sense. As a newer member, I soon sorted out who seemed to be highly regarded around here and actively seek out their responses, while keeping in mind that old adage about various ways to skin a cat. Many of these people have contributed to greatly expanding my knowledge of my car and I, too, thank them for this.
If a post is based on "obscure details that no-one cares about", the members vote with their feet by not reading. So be it. Move on. New topic! There's plenty more to choose from!
Forum members are all big people and have the freedom to chip in whenever they wish. They are also protected by whatever degree of anonymity they choose to utilise.
I can't see any reason why a forum member should feel disengaged or disinclined to post/reply.
Lastly, as to the future of the Model A hobby? Frankly my dear, I don't give a damn!
I'm here for the here and now! Like 31 Model A (Post 2), my kids aren't interested and will probably sell my car when I'm gone.
I don't have control over that, and there are plenty more things of greater importance in the world to worry about.
The world changes. The way I see it, many/most "old car people" seem to be interested in something that harks back to their own childhood (I'm an exception to the rule), so many collectors these days are getting into 60s and 70s cars that, despite a passing interest, I have absolutely no desire to preserve.
I do know this - whatever they do now or in the future is not going to interfere with the enjoyment I get from my beautiful '28 Phaeton!! That's enough for me and I'm going to keep driving it as long as I'm able. After that . . . .???