A while back I was taking pot shots at some distant infantry with my DMR, just single shots with plenty of time to make sure I had a high chance of hitting them. Suddenly a Scythe flew down right as I took a shot, and it was apparently enough to blow it up. Probably one of the most surprising kills I've ever gotten.
The balance between ground and air has improved a lot since the beginning of the game, mostly propelled by cheaper G2A launchers and more people being able to afford bursters and sky guards. The AA buff a while back helped too.
Air still obliterates unprepared infantry, and most infantry are geared for anti-infantry combat. I've been gunned down almost instantly by ESFs with the high RoF cannons. I can survive a missile pod storm in the open if I'm lucky, which I'm fine with, but I can never do anything to retaliate unless I happen to have a G2A launcher. Dumb missiles are just too slow and innaccurate to be effective at anything beyond 50m.
Aircraft, including liberators, just need to feel more like actual aircraft and less like flying tanks. Not enough to be destroyed easy peasy, but it's kinda silly that ESFs can take a tank round, dumb missile, or an entire clip from a machine gun and survive. If a pilot is slow or dumb enough to take one of those things, then they deserve to die. Instead they just fly off and repair, costing them nothing but a little time.
Of course, the AA weapons we have now are perfectly fine against aircraft. If aircraft get nerfed, so should those. This means that ESF canons would get a nerf, but there could be some sort of damage bump to aircraft's canon damage against armor to keep them where they're at there, because armor-versus-air combat is just fine now (Except eating tank rounds and entire clips of MG fire).
One thing I'd really like to see is a burster for heavies. A single burster isn't really ever a massive threat to aircraft that aren't sitting around being stupid, but it'd be nice for non-MAX infantry to have a viable, non-lock-on AA weapon.