I haven't had much to say about the Apple Watch because there are so many things we don't know about it yet. But there are some interesting things to speculate about. One idea that's been floating around the Apple developer community is that apps for the Apple Watch will be extensions of iPhone apps. They'd run on the Watch, but be downloaded and installed as extensions of an iPhone app, and get to take advantage of the shared data container used by iOS app extensions.
At first blush the idea makes sense, but the more I think about it, the more I don't think it's the way Watch apps will work. Ben Thompson pointed out that Apple is thinking long-term about the Watch.
This approach – the one that Apple chose – allows the hard work of UI iteration and app ecosystem development to begin in 2015. Moreover, that iteration and development will happen with the clear assumption that the Watch is a standalone device, not an accessory. Then, whenever the Watch truly is standalone, it will be a complete package: cellular connectivity, polished UI, and developed app ecosystem. It will be two years closer to Digital Hub 3.0 than Alternative #1 or #2.
The tradeoff is significant confusion in the short-term: the Watch that will be released next year is not a standalone device. It needs the iPhone for connectivity. To be clear, this is no small matter: the disconnect certainly tripped me up for a week, and if the feedback I’ve gotten is any indication, it continues to befuddle a lot of very smart people.
Although today the Watch requires an iPhone for connectivity and other assistance, Apple is clearly looking forward to a day when it does not. With that in mind, it would be silly to constrain apps to mere iOS extensions. Why design an app ecosystem around the presence of an iPhone if your long-term goal is to make the watch a standalone device?
I suspect that Watch apps will be installed and managed via a connected iOS device, but will run more or less autonomously. Something like Handoff will be used to pass data back and forth between the Watch and the iPhone. In the short run, Apple may also offload computational tasks to the iPhone CPU to save battery, but that will happen behind the scenes in such a way that developers don't have to give it much thought. Over time, as the Watch becomes more powerful, it will gradually hand off fewer tasks to the iPhone. By making Watch apps independent of an iOS app container from the outset, Apple can make this transition as seamless as possible.
Of course, we'll know a lot more once we get a look at the SDK for Watch apps, hopefully sometime this fall or winter.