New perks! Mines etc.
More Cosmetic oriented awards and braggin rights, for completing specific tasks as well as getting improved and better guns and gear. More melee choices, maybe hand to hand combat.
Getting xp for doing the right strategic choices on the battlefield as holding an area, flanking and staying with your squad, and obeying the squad leaders orders as well as him getting points for giving them.
Squadleader should be able to carry out commands eg. the combat rose in the BF series.
Real Hardcore mode with no, zilch, nada nametags and you should be the one who decides when your soldier speaks and therefore is in danger of being spotted. Keep the voice commands as: Contact! Move in! etc.
"BLIND fire!" shooting round corners or from cover.
Hardcore mode with much deadlier weapons and injury mechanics. A soldier shot in the leg should slowly bleed to death and require the attention of a field medic before he kan be carried around much like that scottish guy in the original COD modern warfare, "put me down here so I can snipe"
More realistic guns, sounds, kill animations and keep the visceral feel with ringing in the ears. But above all! bigger and better maps with better graphics and complex chokepoints and realistic outdoor terrain as well as urban warfare. I know that the kids dumbs down the grafx in order to spot enemies easier and get more FPS as well as frags, hell you should´ve seen how pretty QW was with mipmap_X and fov 130..