User blog comment:Argorrath/Treyarch posts a message of zombies; possibly hinting to a DLC 4/@comment-7965062-20130731122229

Idea 1: Map will be like Mob of the Dead - New universe with it's own storyline.

Idea 2: New Crew somehow will be teleported in 1917

Idea 3: New Crew gets to Agartha and finally end Zombies storyline for good.