First, there will not be healthpacks in GR2. Period. The player and teammates can give medical attention to non-lethal wounds, to get an incapacitated teammate mobile. The Ghosts, just like real Special Forces soldiers, are trained in providing combat medical attention. Medic does not fully "revive" a teammate. It helps a teammate that has been incapacitated (from a non-lethal wound) into a wounded state, where their performance suffers appropriately. If you do not provide a medic to an incapacitated teammate, you will lose them from the mission.