Previously, the development roles on the Call of Duty franchise alternated between Infinity Ward and Treyarch. Now, Activision has announced that Sledgehammer Games is coming in as a third developer for the series.

This will move the two year development cycle to a three year development cycle for each studio. Sledgehammer is already to finish up development on the 2014 installment of the series. So yes, while the development cycle per studio is at three years, there will still be annual releases of everyone's favorite FPS.
"For the first time, this years Call of Duty game, and future Call of Duty games, are being built on a three year development cycle," the publisher also revealed. 'There are several advantages to doing this, the first is, of course, quality. This will give our designers more time to envision and to innovate."

Ah yes, I anxiously look forward to that innovation that is promised! Innovation is one key aspect that has sorely been missing from the franchise for quite a number of years now.