It sounds like the developer is really aiming to flesh out the side campaign, describing it as the “most ambitious zombie effort ever”. It’s not yet clear how Treyarch intends to overhaul the established formula, but the developer has promised deep integration with Call of Duty’s premium subscription package, Elite.
To further the speculation, Activision Tweeted a piece of artwork from the undead endeavour overnight. It’s a teaser so doesn’t really reveal much, but it shows a scantily clad woman standing upon a pile of corpses. Someone tell her she might catch something.
Presumably we’ll have to wait for an official reveal before we get any more information, but we’re going to speculate that Black Ops II’s zombie mode will feature a plot of some kind. After all, it's something the studio experimented with while producing the original Call of Duty: Black Ops’ DLC.