Sledgehammer is working on the new Call of Duty for this season. Rumors pointed out that Sledgehammer could be developing a new iteration of Modern Warfare series.
Aside that, Eric Hirshberg, stated time ago that this year Activision would focus on the next-gen hardware to create the new Call of Duty game. PS4 and Xbox One would be the main development platforms and Xbox 360 and PS3 would receive a port.
Supposedly, High Moon would be developing those ports for PS3 and Xbox 360. The studio known by some Transformers games and Deadpool, would be hiring new employers for a high profile first person shooter for Xbox 360 and PS3. Also, there is a position for Senior User Interface Engineer. Activision demands confidence in the Radiant Engine, a level editor used in the Call of Duty franchise.
Check out the Activision’s apply here and here.
Therefore, Sledgehammer would have delegated part of their functions to High Moon in order to take advantage of PS4 and Xbox One hardware’s.