User blog comment:Damac1214/Call of Duty 2014 Being Developed by Sledgehammer Games, Call of Duty Moving to Three Year Development Cycle/@comment-70.95.184.128-20140207023406/@comment-5358304-20140208025023

Apparently IW has something in a contract somewhere saying that they are the only ones allowed to release a CoD game set after the Vietnam War. Treyarch got in some trouble for having part of BO2 set beyond that. Its always possible they've changed it though.