Smartwatches, sure. I have one and it's definitely an improvement over my phone alone when it comes to email and messaging. Still, I think there's potential for a Glass like device to be even more convenient.
I'm not too familiar with Cardboard, but I don't see how it's related.
Google Cardboard is a piece of cardboard (& software app) that you fold up into wearable - if quite dorky - glasses that hold your cell phone about 2 inches in front of your eyes. It's not exactly stylish, but it works - you do get a real VR experience - and it's completely free. It does augmented reality as well, using the cell phone's camera. One of my Googler friends showed me a cool demo where if you stared at a QR code in a magazine, you'd see elves and magicians battling it out on top of the pages, like a storybook come to life.
One of my wife's friends is doing a startup where you can print out the "gun" for a first-person shooter as well, so you get an immersive VR experience using nothing but your cell-phone and a couple pieces of cardboard:
I got to spend a day on the show floor at SIGGRAPH this year and AR/VR was the big trend. Most of the VR demos felt empty and lacked soul, but the Realiteer GermBuster VR demo was a blast! Definitely the highlight of the VR demos. I guess it demonstrates that (relatively) low-tech doesn't keep a game from being fun :-)
Isn't that the idea behind smartwatches and Google Cardboard?