I've just thought of a great product. Which can probably be integrated into the alleged Apple Smart-watch.
Create an arm-band instead. It won't require the level of miniaturization needed for a watch, and the arm band can act as both a motion controller (like Myo) and a fitness tracker (like Jawbone or FitBit).
Couple that with Apple's iOS and you have an amazing new experience. Automate your home, track your health, and communicate with friends and family. Creating a single fluid experience is key.