I had a thought regarding free to play etc. The versions of it I have seen are predicated on fairly gamey things like "crew experience" or some kind of magical minutia about engines and bullets. That is all very well for people who like that kind of thing, to me it always seems completely fake and just distances the player from the simulated experience of flying which is this games strength. Perhaps there are incremental upgrades that would not be of the usual f2p nature but would be about the experience. For example maybe the F2p player would just get spat out into the air randomly in some random airplane above some random base playing for a random side with 10 minutes of fuel and no bombs. Sell bombs fuel and bullets and control over where you take off etc. but don't make there be too many choices before it is just 15 dollars all you can eat. Maybe have rewards for the perks that can turn into bullets bombs or fuel. I don't know, you would have to test it, you would also have to explain it well. As it is it is pretty all or nothing and maybe too many false choices, (too many f2p arenas that are very underutilized and don't seem to be a draw for new players.) I still think that this would be a good game for E-Sports but at the moment it is too hard for people to "get." I think air racing might be worth exploring, it has the basic arcade simplicity that kept people putting quarters in and might lend itself to scheduled races. Maybe you could win points to by bullets with? Just spitballing.
Regardless this is clearly difficult and might need real market research/psychological expertise of the food pellet/electric shock type. Which kind of sucks.