Nintendo does not need a graphical successor to the U

[sidmeiernintifan]

What would happen if the Wii U were to become successful in the middle of the generation?
For example, lets imagine in 2 years Nintendo is able of selling it for USD200 without losing money. And the casuals, now that almost a decade has passed since the first Wii begin to buy it a lot, to the point that most Wii Us would be sold from 2016 on.
Wouldnt Nintendo in that case be forced to support the Wii U for at least 8 years? If the majority of the customers buy it at that time, they will at least expect support for 4 or 5 years.