Shouldn’t be too difficult to pull off, as they would just need to copy n paste the game mode (or at most have a template from previous games).
We aren’t getting any extra maps until May 2022, so we should at least be able to make custom games in forge. With MCC, you could have some fun downtime in between competitive games to play splatter monkey or speed halo, but with Infinite its purely competitive play. Gets old fairly quick.
Also the snowball gamemode from Halo 5 needs to come back.