Actually, HT and Pyro have experience and data in this area. Years ago, they did a WW1 version of Warbirds called "Dawn of Aces". This was an unfortunate name, because everybody naturally called it DOA, which turned out to be rather prescient
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DOA was a very good game, as you'd expect given who made it. The problem was, it never attracted a large enough customer base to support itself, let alone pay off its development cost. The company HT and Pyro then worked for, which controlled WB, also provided a lot of other online games, but was going broke so needed to get more customers. Thus, DOA (and a space version of WB, too). But despite pushing DOA very hard, including giving folks lots of free time on it, all that happened was a few WB players would go do it for a change of pace periodically when they were really drunk--few, if any, new customers showed up for it. AFAIK, DOA went down the tubes at the same time that whole company assumed room temperature, and hasn't been heard from since.
It's too bad. I like WW1 planes and still play RB2 with that cool mod pack Full Canvas Jacket. Back in DOS AW days, I used to fly in the WW1 arena every Friday night, despite the furballs being too much for the host to handle. But AW's WW1 arena never had much use at other times, kinda like the CT here.
Maybe someday HTC will dust off their old WW1 plane data and do AH WW1. However, that'll only happen if HTC gets to a point where they don't have to worry about making money off it.