Sorry to burst your bubble, but HTC has said that many times. AH is only a WW2 game. Only aircraft that served in WW2, saw combat in WW2, and were around in (at least) unit strength in WW2, will be considered for addition to the game.
HTC hasn't ruled out any other games, but honestly? They've got their plate full with just 1 genre. I don't think they could handle making a WW1 or korean scenario, unless they let AH die totally (and that's what keeps them in the black, so they won't be doing that, now will they?)