How many third party games are there for the Playstation Move, Microsoft's Kinect or Wii Fit? How many third party games are there for the Wii? How many weeks will it take for the Wii U to have more third party games than Playstation Move, Microsoft Kinect, or Wii Fit combined?
I think you use the term third party because Kinect mostly sold 1st party games in the above 10Millions?
Alot of the things that cause 3rd parties to support a piece of HW, whether an add-on or a whole console, has to do with business push. The business push behind the Wii and the WiiU is what explains what you're getting at, but none of that _has_ to couple with a new console. In other words, it's up to the maker how well it does and how well its supported, unless one business partner (3rd party) has that much influence, but it's more the exception than the rule, even more so when it comes to Nintendo.