I think they've gotten too carried away with the campaign stuff. Too much focus on Halo lore and not as much on competitive multiplayer. Btw, H4 should just be all remakes.
Halo CE: Sidewinder (or Avalanche)
Halo 2: Coagulation, Lockout, Waterworks, Colossus, Terminal, Turf, Midship, Containment, Beaver Creek, Sanctuary, Headlong, Relic, Burial Mounds
Halo 3: The Pit
15 maps right there. If you have to have a Reach map in there it's either Powerhouse or Swordbase.
I don't want to even see 343 try to attempt making original maps. Why? I want a Halo game that's fun NOW. There's a chance they could screw up and I'd rather see them screw up with H5 making original maps. You just know they'll have something stupid in there if they try something original. Low-G all over the place. Shield doors. Laser doors. Dumb Halo lore related stuff.