Why didn't it happen? Basically, the filmmakers (headed by director Richard Raaphorst) never got the money they needed. It appeared that they had financing lined up in 2008, but due to unspecified behind-the-scenes wrangling, money was never secured, and the project was shelved in 2009.
Will it ever happen? Chances seem slim, with the last update on the movie's website (in May 2009) reading "WCS is dead in the water." Raaphorst and company have moved on to other projects that may incorporate some of the ideas from Worst Case Scenario (including something called Army of Frankenstein), so the project may morph into something else. In the meantime, the 2009 Norwegian movie Dead Snow broached the Nazi zombie subject matter with some success, perhaps making it more difficult for a similarly themed film to get off the ground.
