Google glass proved that people will not wear wonky headsets walking around most of the time.

But what if you just had an attachment to your phone, like the Apple Watch. Instead of making the glasses the device, it's just a peripheral that you pop on as needed.

Honestly the fact that this doesn't exist yet makes me think I must be overlooking some major downside.

I think we'll do less and less of the actual computing on our persons. Carrying around a device with the processing power of a smartphone will be unusual. I think the average consumer would prefer a sturdy, reliable device that lets them browse the internet, message, take pictures, and listen to their music without having to be updated every twelve months. I think they would even be willing to sacrifice speed, as long as the network was reliable.

The fact is most people don't need all of the features of their smartphones today. They have those features because developers have to justify their paychecks, not because they are actually useful. If society manages to survive long enough for stable, reliable internet to be accessible in most places in a given country, I expect smartphones will decline in popularity rather than continue expanding.