I was thinking perhaps a new game type that features loadouts similar to how elite slayer set up is.
Air Assault
Assault Rifle
Magnum
Jet pack
2x frag
Recon
DMR
Assault Rifle
Sprint
2x frag
Marksman or Sharpshooter
Magnum
Sniper Rifle
Sprint
2xfrag
Operator, Guard, Security, or just plain Armor Lock
Magnum
Shotgun
Armor lock
1x frag
Medic
Magnum
Assault Rifle
Drop Sheild
2x frag
Infiltrator
Magnum
Assault Rifle
Active Camo
1x Frag 1xPlasma
Demolitions or Grenadier
Magnum
Grenade Launcher
Evade
4x Frag
Something like that anyway but balancing issues would surely need to be looked at long and hard first. I noticed in big team battle games you get 128 extra rounds for the AR, but in slayer you get 64; perhaps they can use that same kind of edit for the sniper rifle and shotgun to keep ammo at a low for campers.
Another thought was more maps to firefight, if reach is getting more DLC in the future that have a falcon or scorpion in them.