Smartwatches could one day make a huge dent in smartphone sales if they add cellular (duh), get battery life up to maybe three days for normal usage -- I charge my iPhone nightly but use it all the time for music, Facebook, other Web stuff -- and make it much more standalone. There are people who would buy this as their phone if they don't need all of the full web experience but want a way to contact others.
Right; exactly. This is precisely the hypothesis that I've been offering, though I'm sure I'm not the first person to come up with it.
Under that system, there would still be plenty of room for various sizes of portable content-consumption devices—iPhone-sized, iPad-sized, laptop form factor, and so on—for the considerable number of people who still desired them. The Watch would merely be the node on the personal network that has the cellular connection and GPS; the other devices would connect to the Watch to access that (and other) data, but they themselves would be intended strictly for display, storage, and perhaps certain kinds of data entry (keyboard, digital camera, video-game controller, etc.). At that point, as you suggest, a non-negligible proportion of consumers would surely decide they don't need to shell out money for a portable (though far bulkier than a Watch) Web-surfing/video-watching/extra storage/etc. device at all.
Some breakthrough in better Bluetooth headsets might be needed because that's where a watch really struggles compared to an iPhone or even iPad.
Really? I have a few Bluetooth headsets, and they work fine for me.
Unquestionably there will need to be significant (though hardly implausible) technological advances made in various areas in order for smartwatches to take over the portable-computer-device market in the way I suspect they will, but I'm not sure that Bluetooth hardware is one of the things that need significant upgrades in order for smartwatches to get there.
I agree, though, that in a smartwatch-ruled portable-tech world, wireless headsets become just as vital as, say, iPads are now. They certainly make phone calls and other voice-centered functions more practicable than they are likely to ever be with a Watch alone.