The Wii says hi.
The Wii was successful because it was loved by the casual market, they didn't care about the Nintendo franchises.
Wii was powered by hype and casual party games. The majority of the audience the Wii attracted likely moved into tablet/smart phone gaming. A small few would have moved Xbox /Playstation and a tiny few would have stayed Nintendo.
The Wii was a fluke, the Wii U is continuing the trend of Nintendo consoles sales before the Wii (a steady decline)