Much of the tech speculation surrounding the iWatch seems to focus on what the mythical iWatch will be, rather than what it will do.
So let's assume that the iWatch is coming out. While we're at it let's take a punt and suggest that Apple's going to make it work, insofar as putting an iOS-powered touchscreen display on your wrist. Battery life is good enough, charging is easy enough, it has good connections (probably wireless), the screen displays the info you need, and the interface (both touch-based and Siri-based) works for what it does.
You're now wearing a thin strip of plastic on your wrist with a curved screen displaying information, and you can press it and do stuff with it. What does the iWatch actually do?
I'm sat at my computer at the moment, so it's hard to see anything that it could possible do that my computer doesn't. Mind you, I could say the same about my iPhone which is sat next to the Mac. A better mental excersise is to take a long walk and imagine what that would be like with an iOS-powered wristwatch. What would be useful?
Here's the functions I think you can expect the mythical iWatch to have:
The Clock App (it's a watch - it will tell the Time act as a Alarm, Timer and Stopwatch)Notification Centre (so you know when to dig your iPad or iPhone out)Messages (hopefully iMessages, but also SMS as well) Music (we're kind of expecting our mythical iWatch to have wireless headphones)Phone (you'll have to speak into it to use Siri, might as well place phone calls whle you're there)FaceTime video (how very Star Trek)WeatherContactsCalendarsPhotosRemindersStocks
What the mythical iWatch probably won't do
Safari (let's start big. You're unlikely to enjoy browsing the web on a 1.5in display)Notes (it's not going to have a keyboard, and Siri isn't going to be fun for taking notes)Mail (see Notes)Newsstand or iBooksApps and App Store (Not until Apple has had time to show developers how a 1.5in interface works)Game Center (you won't be playing games)
And we're going to put these in our mythical iWatch unsure camp
MapsPassbookCamera (unless the lens is somehow integrated with the rear of the device, not impossible)FacebookTwitter
So what have we got? A device that does some of the things the iPhone does, but not all of them. And some of the things the iPad does, but not all of them. It's that third-device that Apple loves, or a fourth device if you include the Mac.
If it plays out this way we can see the iWatch being designed to kill the smartphone. It is the device you have with you all the time that lets you place calls, send and receive messages, and tell the time. All the stuff you used to do with a feature phone before the iPhone came along and put the mobile internet in your pocket.
But why would Apple want to kill off the smartphone? Because it controls the iPad market, and people don't need an 4G/LTE iPad or iPad mini and a 4G/LTE-powered iPhone. Apple is controlling the tablet market, but its grasp on the phone market is looking increasingly shaky, You don't need an iPad and iPhone (although owning both is preferable to owning an iPad and feature phone) but you do need to still be able to place calls and receive SMS messages. That's why people who are forced to choose get an iPad can choose a cheap Android phone over an iPhone. It's just to make and receive calls.
Everybody says Apple should make a cheaper iPhone, and perhaps that would help. But Apple doesn't like to just strip things back, it likes to make things different. The iWatch would certainly offer less functionality than an iPhone, but in such a radically different way that it appears to be a step forward, rather than a step back. People who bought iPhones would buy iWatches; they wouldn't buy iPhone nanos.
Is the iWatch the cheaper iPhone nano that everyone's asking about. It would be a typical Apple ballsy move, one that shifts the goalposts while giving people what they really want. A cheaper way to send and receive messages and calls, without cutting in to the app market of the iPhone or the large screen web surfing of the iPad.
Time will tell.