If you want my opinion on what I think the "next big thing" will be, I would say augmented reality (AR).
We've already seen a lesser form of it with the Pomemon Go craze, but imagine if AR were done right using a dedicated device. I know Google tried and failed at this with Google Glass, but they weren't considering practicality when they made that; nobody wants to put on some goofy glassses with blinking LEDs, no matter how hip you try to make them look. But if someone could make an "eye phone" using contact lenses (something many people already use every day), I could see this blowing up more than Pokemon Go did.
On another note, I've been keeping up with these
contact lenses (well, the idea of them at least) since I first read about them in 2008.