Could the next Call of Duty be gracing Nintendo's next generation console? Signs point to "yes."
Previous Call of Duty games, including Modern Warfare 3 and Black Ops, have graced the original Wii. Given Wii U brings Nintendo in line with the current generation of consoles, it would be a far easier port for Activision to pursue.
The LinkedIn profile of one Randall H (via IGN) specifically mentions QA testing on both PS3 and Wii U. According to his resume, he's been working at Treyarch for the past four months.
Black Ops 2 has only been announced for PC, PS3, and Xbox 360. While a November release is secured for those platforms, it's unclear when a possible Wii U version would arrive... mostly because the console still has no announced release plans.