Two simple things that could give a boost to the multiplayer
1. Characters from the campaign should become available in the multiplayer.
2. The ability to create custom classes. (what team you're on should not determine which weapons your chosen class uses.)
SEGA, please support this game. I personally feel this is the best 3rd person shooter since gears of war 1 and it would be a real bummer if this game drifted off in to obscurity without getting some sort of DLC.