the changes you seem to want will continue to change halo from its core mechanics.
The core i want to stay the same*. I don't see AAs or equipment, or parkour-like elements changing the core. They're... enhancing elements. Naturally the implementation must be carefully done of course and must not damage or negate core elements.
What i like about Halo is that is core is so good, good and important movement (in theory, slow movement speed and heavy inertia are no good of course), excellent fluid controls, fun core game mechanics (grenades-melee-shooting trinity, with regenerating health done in fun way that also makes sense lore-wise) combined with excellent integration of vehicles, generally fun and satisfying if a bit unimaginative weapons and limiting the carry capacity to two weapons, no ADS, and for multiplayer, map control and knowledge being such a big part of the game.
But i want something more on top of that. (And naturally the core features must be tweaked for perfection, specifically movement should be made better, faster, more responsive).
In an ideal world, i'd prefer every single game to be a revolutionary but that's not going to happen so i want evolution. Concrete one, not just "we tweaked some shooting stuff and added a couple of weapons to round out the sandbox". For both multiplayer and campaign. (Both can have different things of course, some ideas are best when limited to one of them)
AAs are a good example of a good idea, but one that is very badly implemented.
They fit in well, they're well integrated and could have interesting effects.
Unfortunately the way they're implemented screws up the "everyone is equal at the beginning" idea, and practically every single AA has negative effects on the game: they slow it, they reduce importance of movement, they reduce the importance of map control and knowledge. I think they could be done in a way they would be actually good and fun.
Though to be honest i'd prefer something new on top of them or swapping them for something else, they're kind of basic element now, not new. Still merely having a good implementation of them would be better than having nothing. (Having them badly implemented and balanced yet again just means i will skip the game, sticking to barebones means i will likely skip the game)
While i don't like Reach, partially due to bad implementation of AAs, i have to applaud Bungie for adding something new to the game.
EDIT * Hell, a big issue about the shooters at the moment is that there isn't another game that replicated Halo's core. It is always ADS or some other shit. Well, the core and interesting (scifi) setting.