The Modern Warfare franchise will reportedly stick around for at least one more year.
According to Siliconera's reliable source, voice work is already beginning on a title nicknamed "Call of Duty 2013," which will take place within the Modern Warfare story arc. The game is slated for a 2013 release. We have to assume that this title is indeed Modern Warfare 4, and that it will follow the now established two-year release cycle that the series has held for over half a decade now. File this one under "No... really?!"
Other details about the storyline include that the main character - or one of the main characters - is "a battle hardened veteran in his mid-thirties with a nihilistic point of view." The always loveable John "Soap" MacTavish also allegedly appears in the game, though this is done through a flashback sequence.
When writing about video games - or really, writing news about anything - you come across rumors on a regular basis. It's my journalistic duty to tell you that Activision planning a new Modern Warfare game is indeed a rumor. However, I think we're all on the same page here in that the likelihood of this being true is rather good.
The source behind this news is the same person that outed parts of the True Crime: Hong Kong script before it was handed to Square Enix and renamed Sleeping Dogs. But you probably don't need an inside man to tell you that Activision and Infinity Ward are still companies, and companies need money to operate, so keeping one of their best-selling IPs around is a good idea.