I bet at some point someone will learn from all the attempts at wearable devices and develop something users actually will like. Or maybe we will decide that something like Google Glass simply doesn't work and move on to something else.
I had an app called Vindigo on a Handspring Visor and later a Kyocera 6035 in the early 2000s that gave the location and mapped pretty much every restaurant, bar, and museum in New York long before maps were an obvious part of your phone.
I think the possibilities of AR are amazing, even though I don't think whatever the killer will be has been released yet.
What about in overlooked user interface technologies? I think FaceID would be great for unlocking the a MacBook laptop. Also, the face that Apple can now get ahold of those sensors for cheap and at scale probably opens up the opportunity for user interface innovation. People like to use touch for certain operations on current laptops with a touch screen, but some of those might be better done with a gesture away from the screen the doesn't cover up the view of the screen. (Or require the user to lift their hands up from the palm rest to avoid gorilla arm.)
Tablets existed before multitouch and the first iPad. It was a thinner form factor enabled by better battery and more frugal processors combined with multitouch which made the iPad what it is.
This is in absolutely no way revolutionary. Not least because some Windows laptops have been able to do it for some time (HP? I forget who did it, but it was awful)
You can do this already for a few years now. Surface Pro 4, Surface book, Surface Laptop all have it. Works flawlessly.
Imagine pointing your camera to find an A/C leak inside the wall, or scanning fruit for their ripeness, or measuring furniture at the store to see if it fits in your house/door. Hell, it could even alert you if you have bad breath.
which apparently is now available as an extra sensor small enough to build into ordinary phones, with just one obscure Chinese manufacturer showing a prototype (at $299 for the handheld, it's probably too expensive for now).
On one hand this is pretty sad. There's no wow factor, no truly exciting product releases. On the other hand the frequent releases mean that you can upgrade whenever and you always get pretty much latest available technology thanks to the yearly incremental updates vendors are releasing.
I'm getting suspicious if anything revolutionary can happen in the consumer electronics space. Companies are too eager to release early instead of keeping the stuff under wraps until it is amazing. Take wearable augmented reality devices as an example. We saw Google Glass years ago and then Microsoft Hololens. Now if somebody actually delivers a reasonably good mass market device in 2019 it hardly feels revolutionary after these prototypes. Same thing with VR headsets and smart watches.