I had a simple thought today, and since I haven't read anywhere about it.
Remember that slide in the iOS 7 announcement talking about car integration? What if that external display and controlling technology has its inception for the rumored iWatch device, and the Car integration is just a second use case for it?
After having that out of the way, let me just get the different use cases I can imagine and enjoy:
- Navigation: the ideal display if you are hiking, walking or riding a bike.
- Media control and display: obvious
- Siri: just a relay to the phone, only needs a nice mic.
- Third party support: the bits are already there, apps can just take advantage of it once apple releases this part of the SDK.
- Fitness: Great display for exercising.
- Geo-Caching and Geo-Location based games: with not having to pull out your phone all the time totally more enjoyable.
- Everything the Pebble does already: Notifications, Messages, etc.
Knowing Apple, the iWatch would not only be an external display, they probably would add a lot of sensors that would actually benefit the user. Movement sensors like the one in the fuel band. In combination with the Geo-Data on the phone this can give you a detailed fitness profile. Probably measuring the heart-rate is something doable as well.
In any case: Even when just brainstorming from the top of my head about that kind of device, there are a gazillion valid, enjoyable, life improving uses for it. The question is not if they will make one, but when it will arrive.