With how unforgiving the game's respawn mechanics are; a medic class would fit great. There's nothing more frustrating than capturing an objective and then immediately dying and having to sit and wait for your team to cap the next objective without you. Maybe for balance purposes medics would have no access to offensive explosives, only smokes and flashes. The medic bag itself could also be relatively heavy in order to prevent medics from being offensively overpowered in general.
I think the game needs a Medic class.