User blog comment:Argorrath/Activision confirms next Call of Duty for this year/@comment-69.211.59.26-20130213214956/@comment-5596583-20130214005119

They switch between the two developers (Infinity Ward and Treyarch) each year, IW doing Modern Warfare, Treyarch doing their thing, though they've sort of made it into a series. This year, however, is kind of up in the air. It might be Sledgehammer, for all we know.

However, assuming it is Infinity Ward, that doesn't necessarily mean it'll be an MW game. They pretty much wrapped up the storyline in MW3 (though, admittedly, they wrapped up the story in MW1 too, but found a way to make it keep going). Personally, I hope it isn't, and if it is they make it different enough to feel new.