I came back after last flying in Tour 134, when my last decent gaming rig died an inglorious death. I finally found myself in a life position to get back with a new system.
I do think some advertising would do the game good.... I remember the uptick in numbers circa 2009ish (forgive me if I'm wrong) when the game was adverted on History Channel. Numbers back then were mid 300's every night.... we used to moan about low number nights at 130....
That being said, this is a niche product that has a niche audience. Basically, you need to target an audience that has a love for warbirds and the money to spend on a computer rig that can handle the state of expectation, graphically, writ large. The younger generation of aviation enthusiasts are locked into DCS at the moment. I don't know how you can interest them in the finesse that was aerial combat of the time period that this game focuses on. It certainly does not help that arcade games like War Thunder jumped into the space as well, ostensibly creating a poor dynamic for those that actually tried to get into WW2 combat. Air Warrior jumped into a wide open business space when it came out... and that space is now pretty crowded for Aces High. (Many of us "old timers" remember paying by the hour on dial-up to fly when Kesmai marketed Air Warrior.......but I digress)
The learning curve in Aces is also incredibly steep, and that leads to many folks leaving in frustration. The community here has also taken a step back from helping new people, IMO, even though some folks do go out of their way to try.
This game has some really great things going for it... Scenarios are second to none, and the flight model is pretty true to form. You simply need to find the right target audience again. Unless HT is simply going to let it fade away slowly, and move on to something new, there is space to make this game pop again, particularly if done in a concise, targeted way.