Made a post here on reddit on the subject:
> Now that the rumors, leaks, etc. have started to subside…What do YOU want for this game?
> I mean, sure, we all want:
> - Playable Elites
> - Black Undersuits (check)
> - Old art style (check)
> - The Flood’s return
>
> And so on…But what about the stuff that hasn’t been openly requested by everyone? Personally, I’m not the biggest fan of removing sprint and I love the Spartan abilities in H5. However, how can we compromise? Here’s my first idea:
> - Choose between “Classic” and “Modern” gameplay modes. Nothing changes visually, just the gameplay. Classic = no sprint, no abilities, modern = abilities + sprinting enabled. Competitive would more likely lean on Classic gameplay or be a new gameplay mode in multiplayer, blending both classic and modern.
>
> Now the rest…
> - Choose your armor. Master Chief’s armor can take on a sleeker style or a more modern look from Halo 4-5. Which armor you chose dictates your abilities. Old armor makes you faster and you can sneak around with active camo (maybe?). Modern armor turns you into a walking tank, basically like Halo 5, but slightly slower and with more HP. You can choose your loadout before any mission. Maybe the player can accumulate a few different sets of armor and choose between them.
> - The Didact returns as an anti-hero instead of a full-blown villain, composed into an AI form. Maybe he brings Mendicant Bias or 343 GS back with him.
> - Blue Team returns. They also serve as Chief’s co-op buddies. You can disable them if you don’t want allies on the field of battle. Instead, the dialogue changes and they talk to you through a communicator, from the ship, instead of talking to you directly. Doesn’t require a massive change to the plot and character development, as a result. Just record a slightly different set of lines and/or add an effect to the alternate sound so instead of talking live with you, they talk to you through a comm.
> - Fireteam Osiris returns as a playable team for 1 or 2 mission(s). They’re secondary characters.
> - Halsey, Lasky and The Arbiter return as supporting characters.
> - Roland is Chief’s new AI.
> - Ancient Humans make a brief appearance. Maybe their tech, as well.
> - The Precursors are enemies in the game. (Simply a variation of The Flood, I suppose)
> - The ability to remotely control certain vehicles like the Mantis and Colossus (which you can also get in), as well as drones. You can control them like you can control the killstreak mechs in Call of Duty. Campaign-only, please! And no killstreaks in Halo, please, that’s not what I meant by it.
> - The Banished appear in the game.
> - Professor Anders makes an appearance in the game.
> - EVERY VEHICLE EVER returns. From Halo 1 to Halo 5 multiplayer to Halo Wars 2. If you can ride it, it should be in. Be it the Mantis, Colossus, H5 Scorpion, Classic Scorpion, Falcon, Sangheili Vehicles, Banished/Brute Vehicles, Grizzly, Phaeton, Kestrel, Hawk, Cobra, Hornet, Wasp…etc. You get my point.
> - More Promethean/Forerunner vehicles.
> - The game allows you to explore the world a bit (Like Crysis), but isn’t open world (Like Witcher or Cyberpunk 2077).
> - Marty returns to do the soundtrack, but works with the composers from H4 and H5, to re-use those memorable H4 and H5 tracks, as well as the classic ones, all while creating new tunes, as well.
> - The “simple stories” motto is thrown out the door. Halo 6 explores and develops characters but isn’t burdened by its need to do so, nor does it all detract from Chief’s story. We also reference things like Forerunners, Precursors, The Banished and other events in the books, but never without at least giving enough context for the players to understand, in case they never read the novel in question.
> - Dual Wielding and Equipment make a return, along with the newer Spartan Abilities and Sprint.
> - Forge everything! From vehicles to maps to…Anything. Most expansive Forge yet, make your own game modes, etc. Let us make realistic-looking vehicles and maps, too, not like in H5, where the textures and lighting are bland. Let us make stuff that looks like the official maps and vehicles, por favor! 
But what about you guys here? What are your hopes and expectations for the next Halo game?