While we’ve heard rumblings that Sledgehammer Games are working on a Call of Duty game, it looks like it’s not Ghosts. According to a tweet from the studio today, Infintiy Ward seems to be the sole developer, or at least going it without Sledgehammer.
A wholly owned subsidiary of Activision, Sledgehammer co-developed Modern Warfare 3 with Infinity Ward. It’s unclear if this absence is due to the studio working on the Ghosts follow-up or an entirely new IP altogether, but without Ghosts, they should certainly have some time on their hands.