The Wii U will have games and content you cannot get anywhere else. The Nvidia shield tablet will have nothing but third party ports and content that will also be available on multiple competing devices. This will also mean that very few games and apps will take full advantage of the Nvidia Shield's capabilities.
On a side note, I think if any console maker wants to stay in the console business, the exclusive content and ease of use will be key essentials. Lately, the PS4 and Xbox One have been losing exclusive content because they are basically PC's themselves, which makes porting games much easier than it used to be. Also, because consoles have gotten crammed with all this multimedia content, which can be done better on other devices, they've become clunky and overly complicated while PC's have become easier to manage than before. This needs to be fixed.
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