Re: Still need that "killer app" ?
Watches themselves being a perfect argument for your case.
Young people today (the lucky bastards!) no longer wear normal watches. Why? Because they've got a phone in their pocket and so don't need one. So even the use-case of the watch itself is dying out. Let alone the smart one. Well reducing really, as I'm sure some younger people wear them and there's still a bunch of old codgers around the place who are in the habit.
I wear a watch because I'm in that habit, and I was given a reasonably nice one twenty years ago. I like to be able to just glance at the time rather than taking my phone out of my pocket. But if I want to look at the date, I don't get my reading glasses out to squint at the tiny one on my watch, I use my phone. Anything that requires more attention than a quick glance means that the cost in time of reaching to my pocket to get my phone is now worthwhile.
So I'd say the one application that would work for a watch for me, would be changing tracks when listening to music. But then I'd need my reading glasses to pick from a tiny watch screen, or I'd need a bigger watch. Or just get the phone out... I still use an iPod Classic anyway, so even if I wanted this, it wouldn't work.
The same problem applies for satnav, when out walking. The screen isn't big enough to be less hassle than getting the phone out of my pocket.
Which brings us to fashion. Fashion brands of watches do very well indeed. And I suspect will continue to do so. The same will power the smartwatch market.
And maybe the tech will reverse someday? And we'll have small enough batteries and processors so that everyone will wear their portable computer as a watch, rather than having to carry the thing as a smartphone. And some people will still have smartphones but as a legacy device tethered to the watch to give them a bigger screen - and something to use as a game controller.