I find some of the points questioned here irrelevent, for example;
1. Mario kart wii sold 3 time as many units as ssb brawl due to a casual gamer demographic Nintendo now doesn't posses.
2. It's established that only Nintendo fans are purchasing the wii u, and most of the people who brought mario kart 8 and ssb brawl are core nintendo fans.
3. Using sales from the wii should be compared to games that are targetting casual gamers (not games such as mario kart 8 SSb 4)
Also it is very hard to convince a consumer to make a $300-350 purchase over one killer app bundle (mk8) however convincing a consumer to make a $300-350 purchase with two killer apps (mk8 and ssb4 bundle) is a shit load easier. not to mention nintendo fans predict this'll be the turning point where the wii u has just enough interest to meet worthy demand.
I could be completely incorrect and that gamers are simply bying the SSb4 and mk8 bundle (there are other games in the bundle) just to wipe their asses until they bleed, but only time will tell.