Social:
Arena (4v4)
Rumble Pit (8 Player FFA)
Doubles (2v2)
Big Team Battle (12v12)
Infection (24 Player)
Rotating Playlist
Featured Forge Playlist
The fireteam leader would have the ability to choose which modes to have active/deactivate when searching in any social playlist. Social playlists would essentially act the same as the MCC Match Composer.
Arena - Slayer (AR/Sidekick), BR Slayer, Strongholds, Oddball, Attrition, CTF, KOTH, Land Grab, Team Snipers (S7s Only), Kong Slayer, Purple Reign, Ninja Slayer, Skockets, Fiesta, Tactical Slayer, etc.
Rumble Pit - Slayer (AR/Sidekick), HCS Slayer, Vampire Oddball, Snipers (S7s Only), Fiesta, Escalation Slayer (Gun Game), Ninja Slayer, Skockets, Kong Slayer, Crazy King, Juggernaut, One in the Chamber (Tactical Slayer Settings. Spawn with one bullet. Kills generate a bullet).
Doubles - Slayer (AR/Sidekick), BR Slayer, Oddball, CTF, KOTH, Dodgeball, Team Snipers (S7s Only), Fiesta, Kong Slayer, Purple Reign, Ninja Slayer, Skockets.
Big Team Battle - Slayer (AR/Sidekick), BR Slayer, CTF, Total Control, Stockpile, Fiesta, Team Snipers (S7s Only), Skockets.
Rotating Playlist - Grifball, Last Spartan Standing, Rocket Dodgeball, etc.
Featured Forge Playlist - Refreshed weekly with a selection of the best Forge maps/modes.
Ranked:
Arena (4v4)
Lone Wolves (6 Player FFA)
Doubles (2v2)
Rotating Playlist
Arena - Slayer, Strongholds, CTF, Oddball
Lone Wolves - Slayer
Doubles - Slayer, Oddball, CTF
Rotating - 4v4 Survivors, FFA Snipers, 4v4 Team Snipers, 2v2 Dodgeball, 2v2 Team Snipers, 4v4 Tactical Slayer, etc.
Finally a Custom Games Browser would be able to fill in the gaps.