I could see them releasing an improved Wii Fit thats not tied to a console. Maybe it would include fitness and diet apps that can be downloaded to it.
Another possible thing is the children's learning tablet that was rumored awhile back. A tablet with fun little educational games featuring Nintendo mascots.
These two products could help them regain the Wii Fit/Brain Training crowd they had on Wii/DS.
When the herd loses its way, the shepard must kill the bull that leads them astray.