I could see a new direction for Nintendo using the Wii U streaming tech they have now.

Being able to connect and use any streaming capable display from their new brand of handheld and friends could just jump right in and add their own handheld or a pro controller, etc., or the extra handhelds present could even connect 3rd, 4th, and 5th external displays for large local gatherings.

And when the external display is out of range the game would instantly switch back to the handheld's screen giving uninterrupted gaming going from a big screen experience to small screen no hassle, no file transfer, no lag, etc.

Essentially it would be a dynamic experience capable of single screen gaming on just the handheld or expanding to multi-screen gaming with a variable number of displays and/or external controllers.