So what do you propose? Surely you see the numbers are dwindling
If it were my game, the first thing I'd do is update all the AH1 models, priority 1.
Then, I would implement a graduated damage model so the part doesn't work factory fresh when it's been hit 19 times, then completely fail on bullet 20. If I understand the system right, the information's available, they've just chosen not to use it this way in the current model. Damage would also affect how much G force you could apply to the plane. Damaged wing, best not pull too hard.
I'd also consider reworking the damage model to add more things to break in the vehicle, stuff like control surface cables, possibly the ability to detonate ammo boxes, things of that nature. Maybe twice as many "zones" of damage, as an example maybe have the current wing bits able to break in half.
I'd also consider changing the map system to allow for overhangs. I've often wanted to build a map that looked like the Badlands with all the funky rock formations.
I'd also hire someone to produce maps, or put out the word that we were willing to pay for maps. Not "if you send us some POS we'll buy it" but "if we like it, we'll buy it".
As far as the actual "game" of the Melee arena, nerf resupply and make a run at incentivizing aggressive behavior. More score/perks if you died with more guys getting assists on you, or something along those lines. Time between kills factoring into points/perks... Not entirely sure how I'd go about it, but possibly have the game detect when you've done something good like a BRD and killed the guy that came in from advantage.
Keeping the game as-is, that's where I'd stop.
If I wanted to really make it popular, I'd set up a game mode that had 2 teams, 4 bases, and the first team to take one of the other side's bases wins the round. Or, have different scenarios, bomb the ships or save them. Destroy the train or save it. Sweep the enemy team from the sky. Bombers incoming, kill them before they hit the factory. Have these come in early, mid, and late war varieties. You'd queue for whichever game style you wanted, and once it had enough players the round would begin. Possibly with airstarts.
For the ADD and wannabe pro gamer crowd, 1-10 man versus deathmatch arenas, FFA every man for himself arenas, CTF, etc. Because lord knows we need to make this an ESport.
Winning would earn you points toward upgrades to your plane like 150 octane fuel, bigger guns, skins, and all the other blahblahblah that the grinders want. It would completely crush the Melee arena and the Melee arena would die, but it would be popular.
And I wouldn't play it.
Wiley.