Okay so I have been thinking about BF3 for the past 3+years and I think:
1. Customizable armor for single player. As you level up (more levels needed) you gain the ability to add either colors/details or extra armor that help in combat. Such as a blast skirt helps protect you against blasts (Duh) a shoulder pauldron helps against blaster fire. Along with these benefits comes detriments such as more armor equals less speed/maneuverability.
2. (Optional) Move the customization's over to multi-player but leave the perks in single player.
3. Pick up able weapons. After killing an enemy you should be able to pick their weapon up. With that said a sniper should have a damage reduction on attack with a shotgun and vise-versa. If you are playing as a specific class then you shouldn't be as good with other weapons as you are with your class weapons.
4. Melee, melee, melee. It needs to be added. With the volume of new and old games that has melee I think that Battlefront needs it.
5. Increased "gore." Not a I shoot you in the head and your head explodes in massive amounts of blood and brain, but how about a blaster hole through it, or blaster holes in a guys chest after I blast him with a shotgun. Simple things like that that make it a bit more realistic.
6. Destructible battlefield. Not to the point where I call in a blast of turbo fire from space and half the field is destroyed but how about some of the buildings the non-essential ones.
7. Better space battles. Way too small and too short. Once I found a method to breaking through and shutting them down from the inside it was game over. So maybe more capital ships (moving would be nice) and alot more fighter to fighter action.
8. A longer storyline. BF1 may be the better battlefront but BF 2 definitely has a better story. Almost no one can argue that.
9. And finally unlockable weapons. Maybe not in multi-player but definitely in single and maybe even galactic conquest. (On the galactic conquest note, more options needed, and role over most of the singleplayer stuff but make it so that you have to earn it again in the conquest)
These are just my thoughts and I have had ample time to digest the pros and cons of each of them. This sounds like my type of BF3.