I found this on the Call of Duty site and have yet to see anything about it.
Jan: 2 Maps
Feb: 1 Map
Mar: 1 Map 2 Missions
Apr: 2 Maps
May: 1 Map 1 Mission
Jun: 1 Map 1 Mission 1 Classified (New Mode?)
Jul: 2 Maps
Aug: 1 Map 1 Mission 1 Classified
Sep: 1 Map 1 Mission
(All Subject To Change of course)
So all in all, we can expect 12 New Maps, 6 New Missions and 2 Classified Drops.
Considering each Map Pack usually came with 3 new multiplayer maps for US$15 (not talking about Zombies), if would have cost us at least $60 for downloads.