I don't know if this was suggested(I've only found about different skins per team), and didn't find on search.
I think that we should have a different player skin for each different weapon, so a Rifleman could have a camo-ish skin, SMG have a more "grunt" skin, shotgun guy gets "Infiltrator" skin, etc.
Maybe on default, there are little differences only, but you should be able to further modify each skin. Would give modders a hell of some great content to work on.
Maybe this could go with the "different skins per team" suggestion, so Blue side is e.g American Sniper(Rifle), Soldier(SMG) and Infiltrator(Shotgun), while Green side gets Vietnamese/Korean guerrila equivalents.