Honestly, I hope it doesn't. I think adding another park in the U.S. would cheapen the Walt Disney World Resorts & Theme parks brand name. Having Disney in everyone's backyard like Six Flags amusement parks would make it lose the exclusive, and magical feel - at least those are my feelings on this.
I'd also like to add that I read an interview with Eisner and Iger, and both said the main focus would be adding attractions to the current parks, with no intention of adding another park in the near future.