For the Apple Watch to actually start to steal more use cases from the iPhone, a huge change in user interfaces has to happen. Since touch input is really only useful for yes/no choices on a watch, voice becomes the primary channel – and Siri will have to become vastly more context-aware and able to carry out complex, multi-step tasks before that can happen.

If Apple's new AI push succeeds, this will happen, but the company has a long path ahead.