Well, nintendo cant compete with specs and third party support of the other systems. So if nintendo wants the wii u to succeed, they need to do three things.
First, get the price down. The system needs to probably be half the price of the ps4 if they want it to be somewhat competitive
Second, redesign. Redesign the system to make the system itself more appealing. All anybody sees is the freaking controller which combined with the horrible mistake of the name confuses a lot of consumers. People tend to think it is an add on for the wii instead of a new system.
Last of all, they need to develop non traditional gaming options. The secret to the wiis success is they created experiences that were not typical gaming experiences. Wii sports, wii fit specifically probably are responsible for moving at least half of those 100 million wiis. Nintendo cant just come out with updated sequels, they need to create new experiences.