@ Max
It's apparent if the Wii had the 3rd party support the 360/PS3 had the sales would be much, much higher. Nintendo basically carried the Wii with their own software. It's a pattern for Nintendo to shift development to its next console around the 4th or 5th year of its lifecycle. Nintendo was also preparing for the 3DS launch. That is why there were huge software droughts for the last 2 years and consequently sales dropped.
If the Wii U gets most of the multiplats then I wouldn't doubt it is going to be the choice console for the mass market. Assuming the 720/PS4 won't have an interesting hook.