I imagine we'll get some kind of Stadium style Wii U game next year. Nintendo is expecting X/Y to be a huge hit this Fall on the 3DS, so it'd only make sense to have a Wii U game of some kind to help boast that systems sales as well.
I wouldn't be surprised if the collaboration is a Wii U game related to X/Y that will be revealed at Nintendo's Fall conference with a Spring or Summer 2014 released planned to try and capitalize on X/Y success as soon as possible.