In an interview with Wired, Miyamoto said this:
Shigeru Miyamoto Wrote:
The goal at this point is that we would make Wii MotionPlus required in order to play Zelda
The bigger hurdle for us is not really whether people have a Wii MotionPlus or don’t have it, it’s whether or not the experience is one where people will think they want to have a Wii Motion Plus in order to experience it.
This means that to be able to play the next Zelda, you need to spend a little extra.