my first suggestion is : implement some tipes of secodary objectives that give a passive bonus if completed, like a premanent rally point, an air drop of ammunition/medkit, light AAA fire, in short something that give a boost to your team if you can complete what the task given to you.
second suggestion : i would like to see a squad sistem like battlefield bad company 2 (idk if new battlefields have it i dont play them) you can be put in squad with on other dude maybe having a 5% xp boost, and having a vioce chat with your teammate and special interaction that you can do only with him (example exchanging weapons, give ammo, and maybe revive him for free).