A lot of the discussion is dominated by the spartan abilities and which should be cut [sprint, pound, charge, thrust, etc]. So i would like to draw some attention to some of the other features introduced in halo 5 that i think are generally pretty universally liked in the hopes that they do return and how they might fit into a game like infinite.
Vehicle Seat Swapping: Everyone loves this. Although if they bring back multi seat air vehicles (which they definitely should) they should probably disable it on those....at least for the pilot.
Spartan Chatter: Helps reduce the gap between solo and mic players, of course mic will and should always be better but i think its a nice little feature that helps solo players. Its not major but it would be nice for it to become a staple.
Orders: I hated the revive mechanic, and I don't want to see squad mates every mission however the ability to order friendly AI would be very useful if it was applied to all friendly AI. For example being able to select a vehicle for friendly marines, perhaps even select individual AI and have them enter vehicles or pick up weapons (press up on ally, press up on hog) would make loading up a AI squad with the best weapons on your scout hog a lot easier.
Artemus Tracking: Personally I'm neutral on this one, its clear it was meant to be more then it ended up being. I don't think its a bad feature tho, although you could argue it makes hunting for secrets too easy. Personally id prefer the flashlight return (I know it was automatic in that one section in h5's second mission but it was kinda wonky i don't think it was done well) but I'm fine either way. Could be expanded to function in multiplayer as a way to show the spawn location and timers for non-power weapons like BR's and DMR's that don't have a weapon pad with a timer. Wana know how long till the DMR is up? press that button. Would give players the ability to find out what they want to know without clogging the players UI.
Stabilize/Hover: This is the only SA I'll mention. It should be toggle-able and maybe have some different button options for those who want it, but i like it. I hope it sticks around and isn't sacrificed so 343 can say to classic fans "hey we cut a SA just like you asked" while keeping all the ones that are actually controversial.
I honestly feel like this stuff alone would have been enough of an improvement to halo to justify halo 5 without the more controversial spartan abilities. (Also remember there is a separate thread for those spartan abilities for those who want in on that discussion)
Seat switching,clamber,and thruster pack stay.
Get rid of sprint,ground pound,stabilizers,smart link,and spartan charge.
Increase base movement speed to compensate for the removal of sprint