2012 - 2,247,216 (launch)
2013 - 3,113,285
2014 - 3,674,351
2015 - 509,493 (estimate for 2015 - 3,750,000)
If the Wiiu can sell 3.75 million unit this year, they are still 9 million away from matching Game Cube numbers. I'm thinking the last big year for WiiU is 2016. Expect sharp decrease before it's eventually discontinued.
**There already rumors of a new console from Nintendo in the works.
**Seem like Zelda will be the last AAA Nintendo consoles on the system release in 2016.
**3rd party support is all but gone
**Nintendo doesn't seem keen on dropping the price, they might simply prefer to abbadon the WiiU for the next console.