from the Call of duty site
"To further augment an already-impressive selection of Core 6v6 maps, we are excited to announce that a number of fan-favorite Modern Warfare II maps will gradually become available to play in Modern Warfare III throughout the live seasons. The initial selection — scheduled to be four Core 6v6 maps that include Farm 18, Mercado, and Shoot House — will become available shortly after launch in a dedicated Playlist"
The critics will say, see told you it's just an DLC or expansion pack.
I am ok with that. We get new operators, new guns, the MW2 2009 maps (which I mostly liked), a new campaign and zombies.
As long as it plays well I'll be happy with it. Too bad DMZ doesn't seem to be getting anything