The other half of the community who enjoys Max units but remains largely silent at all the QQ torchforky would come out in full force to complain. If/When that died down, and if/when there was a recovery, the new thing everyone would complain about is how powerful HA is compared to the other infantry classes. This already happens now some, but removing the Max class would bring attention of this to the foreground. I believe that if you remove Max units you will probably loose at least a third of the game's population across all servers.
For AA new counters would certainly need to be created or at the very least the others would need to be buffed. Nothing holds air space from the ground the way a duel burster Max does, Skyguards are great against slower air, but I find they make me flee more often than die when I'm in an ESF. G2A locks are similar, as they make me flee more than die. Base AA turrets can get kills, but they are in predictable locations and can't really defend themselves. The only real leash to reign in the A2G guys will be A2A fighters.
Ground vehicle play may see some overall improvements, however they will be more vulnerable from A2G attacks than ever before. Often the saving grace for an AMS is the Max guarding it and switching AI/AA/AV from the terminal to defend against the appropriate threat. The use of walkers and Rangers would need to increase.
The ability to set up AA and AV nests in clever places would be hindered and easily wiped with air, as would defenses and breaches of the notorious choke point territories. Bases that have 'A' point still inside the tower directly underneath an indestructible spawn room, would never have 'A' point taken and held with a 50/50 or even 55/45 pop ever again.
If you remove Max units form the game many players will likely stop playing completely and all you will have left is the extremely vocal minority who tell us about how much they don't like Max units every week. Just like the A2A locks and coyotes get complained about every week by the minority of pilots who don't like them. Torchforkery.