If you were wanting to keep with four classes instead of five then I guess the Assault class could become the Medic class, with an aggressive damaging focused training path and a less aggressive healing focused training path.
But they we'd have a situation from BF4 days where people in chat would complain about people not running defibs when they should etc..
Plus many people really love assault having the redeployment beacon so unless it remains on the aggressive training path as a gadget option, or it goes to Recon but the spec ops training path gets a rework with Carbines as a signature weapon, then that might keep them happy.
Could introduce spec ops a fifth class, spec ops gets some of Assaults abilities, like the beacon but have more of a focus on stealth for one one training path and aggressive play for the other.
Assault now has the ability to drag revive everyone, one training path is aggressive focused, the other medic focused. Still retains some of it's original gadgets and gains some new ones.
But that might be reshuffling things a bit too much VS just doing a fifth Medic class but it would be interesting.