If they remake the game, they'd have so many chances to screw it up.
If they "fix" the glitches, like double meleeing and backpack reloading, or tapping the trigger to make the pistol accurate, I would be very disappointed. Double meleeing wasn't easy like a BXE, and you left a live nade at your feet, so it was risk vs reward. And if they change the pistol to be inaccurate, then I personally believe it would change the core of the game.
Pretty much everything needs to stay the same (weapon timing, teammate spawning, aiming mechanics, physics engine), except for a few things. I personally wouldn't mind if they created a crouching grenade throw animation so you don't get locked in place for a second.
What also should be fixed is when you're blown into the air and your rockets come out of your side instead of where you're aiming (don't know what this glitch is called).
Graphics and map geometry need to stay the same, as I think Halo 1's multiplayer is absolutely timeless. But an updated 720p engine that's optimised for the 360 to eliminate any frame rate issues would be desirable.
I think the lan code should be altered to remove the delay seen offhost.
Custom game options, theatre and forge isn't a top priority for me, as the game holds up on its own merits.
If this ever is confirmed, I'd be very anxious about them messing up. There are people who still lan this game every single week (chaosTheory_s3, his lantages are some of the best Halo videos ever), so people like him know Halo's multiplayer more than most people, including 343 and Bungie.
tl;dr- Make it pretty much exactly the same as it was on xbox, but optimise the framerate.
[Edited on 10.19.2010 4:13 PM PDT]