I have been hearing many people talk about wanting another ODST, but not as a standalone game. There is also plenty of lore in the books that isn't flushed out in the game that could be explained in an ODST gametype with various missions from stealth, to hostage rescue, to plain out shoot outs. It would be an improvement on spartan ops, which gets stale after you play it the first time. You could do missions different ways, and learn about what happened whilst chief was frozen.