You imagine completely wrong. In fact you use straw man augments constantly, rather then making the obvious assumption I have a huge vested interest and desire in making AH succeed.
I mean no disrespect. You know I respect you and your work.
But if I could use my Jedi mind-control powers, I would place a thought into your mind like Inception; your vested interest is in making HTC succeed. A subtle change. There is no reason AH has to be the hill HTC dies on.
Also, I would suggest you define "success" for Aces High carefully, and realistically.
Aces High has succeeded. It was one of the pioneers of online combat gaming. It was the internet Shizzle in it's day. It's lasted 20 years and all its competitors are either gone or zombie husks.
Aces High continues to succeed in that I think you are capturing about 85% of the possible market that would be interested int this particular design implementation. The ROI it would take to get the last 15% is probably not > 0.
I don't think there is much more juice left. I have little faith AH could acquire significant numbers of new players. I can't imagine a realistic scenario where the numbers spike back up to 500 players. I wouldn't spend any money trying, but anything you can do for free, why not. Your best bet is to target past players and re-monetize them somehow. That is not failure, that is having carried AH through it's entire 20yr product life cycle curve and squeezed all of the life out of it anyone could get. That has been quite an achievement for a company with such limited resources.
But you can not alter the market forces and trends. You don't have that power. And AH is not magically immune to market forces.
Other than that, I think you should be putting AH in sustaining mode and looking for new hunting grounds. You still have your knowledge, experience and infrastructure. That is the best thing you can do for AH as well, as a healthy and profitable HTC is the best way for AH to ensure it's long tail.
Which is of course why you started WO:P, but...well that's a whole other discussion.