An article on latimes.com about the blockbuster launch of Call of Duty: Modern Warfare 2 concludes with word that a third team is now making Call of Duty games and another mention of possible MMO plans for the military shooter series:

As Activision seems to be discovering this year with Guitar Hero, there's danger when a title is overexposed with too many iterations. Nonetheless, the publisher has aggressive expansion plans for Call of Duty. Although Infinity Ward and Treyarch have produced sequels in alternating years since 2005, the publisher now has a third development studio working on future versions.

One person close to the company said it also was considering adapting Call of Duty as a massively multi-player online world. The genre, in which Activision's Blizzard Entertainment subsidiary is a leader, requires huge upfront investments but can be very profitable as players pay a monthly subscription fee.