Miyamoto said this to ONM:
“I think it sold lower than our expectations but on the other hand it was a really unique game, I have to say. And also, even today, we are receiving several different offers from people in the field of music education, so as far as Wii Music is concerned, I think it still has great potential. And in the future there might be some developments.
We may want to think about the possibility of making some improvements, based upon the original Wii Music.
Unfortunately we don’t have any news we can talk about at the moment. But like Wii Fit Plus, it’s not really a sequel to the original Wii Fit – but we have added some features to improve the overall experience. It’s a kind of an enhanced version of the original Wii Fit…”