I used to play on HT KotH servers religiously before taking a couple years break from ArmA all together. Im back now and see the server still plagued with problems and complaints I saw when I left. Here is a no bullshit, no holds barred, honest-to-god-fight-me-if-you-dont-like-it list of things that I think could boost up HT KotH (especially now that Sa-Matra has left the picture).
A hard nerf to Tigris and Cheetah AA IFV's. This can be done in multiple ways - My favorite is the removal of thermal scopes on these vehicles specifically. Disabling Thermal Scope would make it harder for AA's to become armored shredders for a majority of the garage players have access to and make people rely more on the radar and locking graphics. Another suggestion would be to limit the cannon ammo on these vehicles so spamming infantry positions means having to spend precious AA missiles on ferrying choppers. I think this nerf alone would make a lot of players happy and would vastly increase the quality of life on the servers.
Adding Tanks DLC vehicles and weapons. I understand you're in the midst of an version update for the mission and I'm 100% certain we'll see them when they're released, but the handsitting is real. It adds more ways to take out heavy armor which has always been a bit of cursed blessing for KotH servers.
Revamping the money system to facilitate an inclusive experience rather than a grind. As it stands, Simple assault rifles and their attachments are far too expensive for new players to access. I was level 40+ when I quit playing and still own very few weapons permanently simply because it was not cost effective. KotH and ArmA 3 do not have a growing audience and trends shift within the community, KotH is no exception. Most of the complaints I see from people who tried KotH and left are "it takes to long to be able to get anything decent, so you're just getting run over by people who've played longer until you have enough money to finally get a decent gun." Lowering the prices of the Assault rifles and the first level specialist weapons (Rahim, MX SW, and the RPG-7) would allow people to make a larger impact out of the gate rather than spending 10+ full matches hiding and praying to be able to afford the gun they want with a useful sight.
If at all possible - add in UAVs and the Recon Nyx. Surveillance is by far one of the most useful aspects of the game that is completely overlooked by the go-go-go nature of KotH. Much of the armor camping that goes on is simply because its hard to find the vehicles hidden 1.5k out. Adding UAVs offers not only direct counters to armor with ATGMs and LGBs, but also a indirect counter via surveillance and lasing. UAVs have limited munitions and, no AA capabilities and no countermeasures - they can be taken down via HMG, Titan AA or via choppers and jets. They're a missing piece to the puzzle of a balanced ArmA mission.
New battlefields. Altis is a huge island and we have a grand total of three cities that we visit. Simply put a change of scenery would be excellent. Alternating between Towers and no towers would be nice as well.