It's ALMOST official that Call of duty black ops 2 is in the works. There is a huge chance that the game will be releasing some time later this year (most likely November)
Rumors have been going around that Activision will be completely done with creating zombie maps . (This is primarily aimed towards the Wii, Xbox 360, and PS3 System(s) .
As most of us know Call Of Duty for the DS/3DS system is created by N-Space , and so if there is another Black Ops game for the DS, then there's a possibility you will be getting some more zombie maps.
There isn't much more information that's been released, but when there is, I will let you know !