If there was to be a multiplayer gametype in ODST 2, I would like to be able to steer a drop pod onto the battlefield.
Armour customization affects certain aspects of your character (ex. Micky's shotgun shell leg strap allows you to carry more ammo for the shotgun, but her runs a little bit slower[I know that's unrealistic with a few shotgun shells slow down movement but it's just an idea], studs on the ODST's gloves could add a bonus to your melee attack but make your reload a little bit slower, ect.), and if there was a multiplayer mode, I'm not sure if this should be used in it, but if it was used in the game, at the very least I'd like it to appear in firefight and campaign.
And since Reach wasn't fully explored in Halo: Reach, I'm thinking something could happen there.
Also, first-person driving, at least for ground vehicles(I think piloting aircraft in first-person would be a little too difficult), as it would add to your sense of vulnerability while driving and such.
Also being able to hot-wire abandoned cars and such(or something different if security is incredibly amazing) as ODSTs would have a greater use for it than spartans would have(especially in the case of The Rookie in ODST[I'm not trying to turn this into GTA]). And since spartans where taken away around the age of six, they wouldn't have really been able to learn how to hot-wire cars, where as ODSTs might have had the knowledge prior to their involvement in The Human-Covenant War. This would also add some sort of mini-game I guess, to ODST 2.
The ability to go prone: ODSTs require stealth far more often than spartans, especially since they lack energy shields.
Also, The covenant infantry should have some sort of night-mode for their armour and weapons so that they're harder to spot at night, as it doesn't make sense for your enemies to look like a Christmas tree at night.
And if the ODSTs in the story were issued combat knives, I think that if we ran out of ammo for our guns we should be able to pull out our knives, although this might ruin the feeling like you have to grab what ever you can find when you run out of ammo. I also don't want Halo to turn in CoD.
The silencers also didn't seem to do much in ODST, I think that they should either have some sort of affect or just take them out.
Quickdraws: since ODSTs will sometimes need to trade speed for stealth, and therefore can't always use jetpacks on a mission, it would make sense for them to have quickdraws, now although quickdraws are climbing equipment, I think that they should be used for something else. Above I mentioned hot-wiring cars, and I think we all remember Jorge from Halo: Reach climbing on the back of that truck and firing away with his turret. The thing was we couldn't do the same thing, now I think quickdraws should be used by ODSTs to hook themselves to the back of civilian vehicles, and thus be able to fire away with whatever weapon they have.
[Edited on 03.22.2011 1:42 PM PDT]