I disagree with the idea that everyone who had a Wii is one of two types. Given the saturation that the Wii achieved, there is no that's possible. Yes, it did have a substantial casual segment but you don't have that many units sold without diversity in your installed base.
The problem for Nintendo was, A) the massive amount of momentum the Wii lost at the end of its life-cycle, and B) the Wii U did not immediately grab people. I think there was a significant amount of new gamers who had their start with the Wii, who might end up purchasing another console. Some of them were kids who might end up looking in a different direction as their preferences change.
After all, something similar has happened before. Some kids who started out with the NES and SNES shifted to Playstation as they got older. Interests can change.
