To be honest I'm not really even sure if Nintendo is capable of selling much more than 20 million home consoles anymore unless there is a miracle gimmick attached to the whole sales proposition. Even the N64 ... if people knew going in wasn't going to be like the NES and SNES in terms of overall support and understood the economics of the cartridge vs. CD decision and everything that entailed ... the N64 probably would've sold considerably less.
A lot of people bought the N64 early on with the expectation that it would be like the NES and SNES.
And to be fair I don't think Sony/MS would sell much more either with the same level of third party support.
People by and large simply don't want a console with a specialized/niche library, when they buy a console they want access to all the games. Wii U is just a return to the norm for Nintendo, taking them back to the trajectory they were on before the Wii.
The other thing is Wii sales really declined fast once MS introduced Kinect and Sony introduced Move ... suddenly motion gaming on a console was nothing special or exclusive to any of the brands, they all had it. That's also a problem with basing your whole sales pitch around a controller -- anyone can copy a controller. Analog stick, rumble pak, wand controller, all copied eventually. Nintendo is probably actually lucky that Kinect didn't launch in 2008 or 2009.







