IMO the movie is just going to be panned as a 28 Days Later remake and have the reviews repeating the usual "braaaiiiins!" over and over.

I doubt it will make much money as Pitt and studio MBA's have already alienated the vast majority of the pre-existing WWZ fanbase. It may have a decent opening weekend but fall off the radar quickly if the word gets out that the movie is just another 2 hour music video.

Almost 2 months of reshoots is going to be very expensive and won't leave much for marketing. IMO they are going the cheap viral route and put up a fake conspiracy theorist or scientist blog documenting a growing number of zombie attacks complete with shaky camera youtube videos which lead up to the movie opening. The first posters will be a simple "WWZ" in large letters and Brad Pitt's name prominently displayed to create curiosity as to what WWZ means.