I know it's a pipe dream but I think given the Galaxy at War setting, there should be one or more MP maps set such that Collectors are fighting Cerberus (as one example) and our team of four has to insert into the middle of the hornets nest to accomplish goals like the existing MP maps have/do...
Gameplay would see a higher 'enemy' count, but since it's a three-way fight, NPC vs NPC would result in overall similar enemies for our teams to handle....
Just a thought