A recruitment ad on Treyarch's website has confirmed that the studio is in the beginning stages of bringing the Call of Duty franchise to a new console.
As initially reported by Gamespot, the ad states that the team are looking for a senior software engineer to bring their "hugely successful game to a new console".
The language being used, in addition to a later mention in the ad referring to adapting "graphics and other major systems in our engine to a new platform", would suggest that the game is most likely a port of some kind.
And the inference from that, if you'd forgive us some speculation, is that the game is most likely being developed for the PlayStation Vita or, at a push, the Wii U. The fact that the game appears to using current gen tech, and is most likely a port, would suggest that this isn't a game destined for an as yet unannounced console from Microsoft or Sony.
Next-gen Call of Duty in works at Treyarch? [Gamespot]