Don't wanna be the bearer of bad news but we might have a problem here.
I think the MP is playing (a lot) too safe compared to the Campaign which tried a lot of new things (with a lot of success) or even Halo 5 (Warzone, Breakout, Sprint, Spartan abilities, etc.. with more or less success.)
MP should be bold and more friendly for casuals.
(although I think that Forge will be a big leap forward)
A 45-player mode with 3 teams (Red, Blue, Green, 15 players) competing against each other to reinforce unpredictability and tension. Or a Free for All mode too.
Taking place on a large map on Zeta Halo re-using assets from the Campaign with vehicles, Forerunner structures, Banished outposts and caves with Sentinels, Grunts, Elites, Brutes, Hunters, Phantoms, etc.. roaming and patrolling on the map and hostile to everyone. And Grappleshot equiped by default (with cooldown).
Drop on the map (more or less where you want) in a ODST drop pod in a cool way and with some equipment.
You gain points by elimating other Spartans but also just by killing Sentinels and Banished (good for casuals and players with low skill, a Grunt or Skimmer is easy and fun to shoot) + by maybe accomplishing several time-limited objectives on the map or whatever (like destroying a AA gun or securing a Forerunner beacon). Best player or team at the end of the game is celebrated (like in Battle Royales).
Something new, shinny and ambitious built upon the strenghts of both structure of Infinite's campaign and Halo's sandbox and multiplayer.
Map set on the ring with Banished and Sentinels/Skimmers AI patrolling it. With some ambient combat/drums music somtimes too like in the Campaign (Heavy Artillery..).
Small caves (as alternate paths or to find Epic Loot)
Forerunner structures (with Hunters, Brute hammer chieftains or Tremonius-like bosses guarding Legendary Loot)
Also a night variant of the map with torchlight + Banished outposts with AA guns (destroy these first to gain points or a AA Wraith, whatever..)
Just letting my imagination run wild and it's hard things to do (+ it would probably weaken BTB playlist a lot) but I wish Halo MP in 2022 would go wild and take advantage of its incredible sandbox and new open-world. I play MP daily but as a BTB/Warzone player, I'm feeling a little underwhelmed. Like it would need more vehicles and more maps if there isn't a PvPvE mode like in Halo 5.