1-2 shot helmetless headshots with any weapon. Helmets buffed substantially with Exo helmet being untouched or marginally increased.
Health marginally increased to prevent center mass TTK being shorter than helmeted TTK. Alternatively buffing body armor to achieve the same effect.
Armor to be resupplied from HQ, aerial supply box, Humvees, APC's, tanks, RCB's, transport LittleBirds and Blackhawks. Each with a unique maximum capacity tailored to their perceived storage size.
Transport vehicles would be the dominant role in armor resupply so long as only they have the ability to drop their supplies. The black HQ box would make the most sense regarding its' appearance. They may as well have a "small ammo box" in them.
Implementing a logistical role like this would require issuing XP and adding mini-map markers to identify drops.
The time for armor resupply should be equivalent to the current HQ resupply timer. This way you can't just resupply armor in the middle of a firefight and you may find it necessary to disengage once you've lost your helmet.
I understand that this would completely change the flow of the game but I do believe this to be a possible answer to the current speed meta.
Maybe medics would actually be medics. Maybe wearing a helmet would actually be advisable in-game, just like in any real warzone.