I think that there should be a multiplayer mode in Reach like StarWars: Battlefront :D!!!!
That would be beast, being able to switch factions whenever you die in mini skirmishes, such as ODST, Marine, Sniper, etc. And there would be two sides! Like UNSC and Covies =D
If you choose the Covie side, you can be grunts, brutes, elites, etc. That would rule! And then you fight against eachother in modes like territories, slayer, etc.!