'Modern Warfare 4' rumor just that, a rumor

Last week an interesting rumor popped up from the "Captain Price" voice actor Bill Murray stating that he was starting work on Modern Warfare 4.

Supposedly the rumor started out when a fan reported speaking with Bill Murray, who told that particular fan that he would be voicing Captain Price in the next Call of Duty game. This Is Xbox first reported the rumor, where he told the fan;
Yeah, on Monday I am off to meet Infinity Ward about the next game, Modern Warfare 4, Im doing work on the sequel to Modern Warfare 3, it carries straight on and I only ever appear in the Modern Warfare games
However, Bill Murray himself took to Twitter to set the record straight stating that he was doing voice work on a Call of Duty title for China, not Modern Warfare 4.

The particular China Call of Duty that Murray is speaking of looks to be Call of Duty Online, but that has not been confirmed as of yet.