[wpietri]

I don't think it's really about getting more life out of the existing battery. I think it's more about better integration with people's lives. E.g., I don't want to have a fit of beepilepsy every time I get a text or a calendar notification. Glancing at the watch is way better.

But as a side effect, I think moving a bunch of watch-friendly things to a watch will let you make the phone bigger. That won't reduce total power usage, but it will increase power availability.