Hi,
First off, this is just an idea IF there is time for it. There are a lot of things that need to be done before things should be changed visual. Anyhow:
Battlefield 3 still uses the "old" method of rendering lighting/reflections in screen space, basicly they were between the transition of old to PBR.
It will be a time-consuming thing, but is it possible to switch to PBR or change lighting properties to something more realistic.
If I am correct, the Color and Bumpmap will be exactly the same, only Specular will need to have some minor tweaks (Colorbalance wise).
Reflection probes are already in-game considering the tone/atmoshpere in different areas of maps i believe.(CoD have had them since 2008).
These days there are a lot of references to PBR methods (UE 4 for example), so there might be a way.
Otherwise;
Tweaking the shaders so that they look better. The shaders currently look "flat". In theory, every object has reflections (basicly a value between =>1f and <0f). In Battlefield 3, this is not the case. So maybe it's interesting to look at that.
Sidenote: What's your opinion? Do you like the look/feel of BF3 or do you think improvements can be made?
Thanks for your time.