While we've heard rumblings that Sledgehammer Games are working on a Call of Duty game, it looks like it's not Ghosts. Infintiy Ward seems to be the sole developer, or at least going it without Sledgehammer.
via N4G: pc news feed http://n4g.com/news/1244410/sledgehammer-games-not-involved-with-call-of-duty-ghosts
via N4G: pc news feed http://n4g.com/news/1244410/sledgehammer-games-not-involved-with-call-of-duty-ghosts