According to a UK PlayStation Magazine, Treyarch has been hiring people to help development the next Call of Duty title which is believed to be a Black Ops sequel. Call of Duty Black Ops was one of the most successful video games in many years, shattering all kinds of sales records, so it makes sense Treyarch would attempt to follow up with Black Ops 2.
If Treyarch is taking the lead development role on this Call of Duty title, then zombie fans can expect to see more Black Ops zombies in the sequel. Call of Duty Black Ops 2 should have an expected release date of November 2012.