Some things that realistically could be done, and should definitely come in the future.

1. Weather: Dynamic weather that a map has a chance to have every match, but only rarely. This could include rain, snow, and sandstorms, tremors, and cyclones.
2. More Commander Voicelines: Battlefield does this very well, and it makes the game more immersive and cool. Like a voiceline for when an enemy aircraft or tank is spotted.
3. Drones: I might not even have to ask for this, since it most likely will come along the way post-release, but just in case, please consider it. Drones as a swappable gadget for the Assault or Recon class that can be controlled via remote would be awesome, being able to take out standard infantry and vehicles.
4. Melee Weapons: I know, it's been asked for a thousand times, but knives and daggers would be fantastic, encouraging players to get up close and defend themselves in tight spaces like on a rush map.
5. More Scenery: I'm talking about spy planes in the sky, aircraft flying over the mountains, other places far away, you name it. Anything that is innaccessable but still cool to look at from far away.
6. More Music Three new soundtracks to consider; one as the match begins, another before you lose, and one before you win. Music is a crucial part of video games, and this would be great to inspire from Battlefield.