Wii U can get some hardware sales only for the Nintendo Games but that's not enough to be successfull with the competition of PS4/Xbone. I'm sure that Wii U will struggle to get 3rd party games even if that gets then it will have inferior version of PS4/Xbone with the same price point. So, why would anyone want inferior version for same price and also almost 80% of the people who buy Wii U will get either PS4/Xbone. Wii U is only for Nintendo Games so its sales will get high when a new game of Nintendo gets released and get back to normal when there aren't games from Nintendo. Nintendo is good at Handhelds where their IP's sell very well for Japan and good in World wide due to the popularity of their games for three decades and also their IP's are just Fun Games mostly like Platformers style visuals and gameplay, where Home consoles are weak in Platformers to become system sellers and they need different experience and gameplays in many games which is possible with 3rd party support.
GAMING is not about spending hours to pass/waste our time just for fun,
its a Feeling/Experience about a VIRTUAL WORLD we can never be in real, and realizing some of our dreams (also creating new ones).
So, Feel Emotions, Experience Adventure/Action, Challenge Game, Solve puzzles and Have fun.
PlayStation is about all-round "New experiences" using new IP's to provide great diversity for everyone.
Xbox is always about Online and Shooting.
Nintendo is always about Fun games and milking IP's.