Call of Duty: Modern Warfare 3 Zombies has done incredibly well for Treyarch and Activision, which could turn out to be a double-edged sword. On one hand, attracting a more casual audience via a mode that is more like Warzone and DMZ is a good thing, as a larger player count for Zombies makes it easier to justify more resources being devoted to it. However, while open-world Zombies modes could be a great way to kill time between full Treyarch releases that offer survival maps, fans are understandably concerned that the wrong lesson could be learned and round-based content could be fully phased out in favor of content like MW3 Zombies.