The main thing I want out of HALO 4 is losing the armor abilities, with the exception of Sprint since it did help in speeding up the game play and made it more interesting in the process. If 343 is interested in keeping armor abilities then they should have them in the form of drops like in HALO 3 with their power ups, that way they can be fought over and provide a more competitive edge to the game. Not only that but giving them a limited time or supply would prevent unbalancing the gameplay, For instance, if there were a jetpack drop, by giving it a small bar that once its used up its gone would keep people from using it ALL game and give others a chance to use it as well. My main concern with the jetpacks however is how everyone would abuse them in HALO REACH. They used it to get in impossible places like perched somewhere you cannot see them or anywhere that is not within the boundaries of the map, so if 343 is going to keep this in their game they need to think of ways to prevent this from happening.
In a nutshell, HALO 4 needs to be as balanced as possible like HALO 3 with its gameplay. For instance, everything had a counter. Overshield had powerdrain, or powerdrain and regen. Main advice 343, LEARN FROM REACH! No one on my friends list has REACH anymore even though they ALL bought it the night of its release. Kinda sad considering majority of my friends I meet playing HALO 3...