User blog comment:Argorrath/Treyarch posts a message of zombies; possibly hinting to a DLC 4/@comment-108.16.56.77-20130731024332/@comment-1615892-20130731064835

Actually I think it may be true since PlayTheGame central made a theory video for dlc 4,and supposedly treyarch gives them info but doesn't let them make it obvious about the map,instead allowing them to drop hints like this