Helping a coworker get started in DCS. Yes, I still work a few hours a week from home. FWIW I told him about Aces High too. He isn't interested. Youngster though, only 47.
Bottom line, without significant changes of some kind, I see no feasible way to bring a material number of new players into AH.
Like the guy on Enigma's discord, I only see the possibility of reactivating previous players for one last merry-go-round.
But why would they come back? They are going to ask what has changed? If they've been gone long enough, there is VR. Updated graphics in 2018.
But I think you need something more. Like maybe a 1 month "welcome back" trial for previous account holders or something. Something. Anything. HTC, would probably have the emails and be in the best position to approach those previous players with a new deal. Something. Anything. Lift a finger. Move the needle.