One thing I'm wondering about would be just how large will this game be? There's going to be a campaign mode, MP mode with probably 12 or more maps, and then there's probably going to be 2-3 maps including Nuketown zombies for the zombie mode, and then there's going to be a zombie campaign.
and to fatedtitan, it's not that hard to imagine a zombie campaign in CoD. it's called it would be a separate game mode where it doesn't follow the whole points thing or fight til you die thing.
It could sort of be compared to how they take perfectly good Single Player games and add MP modes to them, but in this case instead of single player it will be zombies survival mode, but in addition it will have another game mode.
speaking of turning good SP games into MP games, that honestly pisses me off, like the god of war series for example. that's probably one of the best single player action games ever and they decide to add an unnecessary shitty MP mode to it