Things I would like to see go away/added
1. Armor abilities- Get rid of them, it makes the game feel too gimmicky. Instead bring back equipment from the Halo 3 days, I really enjoyed the idea and game play of them in Halo 3 and I think it adds a nice dimension to the Halo game play experience. This should be easy by using the current armor ability button as the new equipment button. There can still be load outs and everybody would get the option to start with an equipment item.
2. Personal Ordinance drops- Get rid of the weapons in the drops. It takes away the fun of going out and fighting for a sniper or other power weapons. Instead just have equipment and power ups in the drops. This would help bring back the skirmishes for weapons while still rewarding the player for playing well.
3. Vehicles- Bring in another flying vehicle, having only one made the game feel empty. Bring in a promethean vehicle.
4. Map remakes- Choose one map from each Halo game to remake. My two must have remakes are Lockout and Zanzibar.
5. Campaign- Campaign was very fun, but needs one huge, wide open vehicle level. Adding a couple missions wouldn't hurt either to extend the length.
That's about all I can think of. Halo 4 is a very fun game, just with a few additions/subtractions Halo 5 could be a instant classic.