Your memory is playing you tricks. "A couple of years ago" AH had more players by any metric, be it pilots per tour, total hours played by tour or population online at comparable times.
When I had last come back around early 2019, the Melee was running around 185 players most weeknights.
The loss rate curve is definitely shallowing. All those who would be sensitive to lack of new development or the lure of the competition have already left. The remaining players are mainly here for the social connections. As long as their friends keep showing up to chat on chan200, they will too. They might complain about no new planes or features, but obviously that is not sufficient cause for them to close their accounts.
The main threat to AH would be HT's health. He is no spring chicken either. And the (probably narrow) age range of the remaining players means that when they start hitting their expiration date, many will be hitting it at the same time. There is no new blood to smooth out the demographic trend. Probably there are very few "new" players at all. Just an occasional previous player coming back again for a while. But they are probably in the same age cohort as the rest and will hit their expiration date at the same time.
$0.02.
