Our current thing is phone/tablet based where you can basically stream real time video to our support staff and each party can draw on the screen, and whatever they draw stays where it is in physical space.
Customers love it, it works great.
Nobody wants dorky glasses that make you sick.
Wow... that's a great way to utilize AR.
Disclaimer: I work at Microsoft, but not on Hololens. All opinions my own, etc.
My favorite use-case is that in nuclear power plants, they have two people do everything - one to do, one to watch (not in a big brother sense, but more in like a pair programming sense), but this means two people in an irradiated environment. With the AR tech, the second person can be in another room.
(Although you run into other issues, like no wifi (or power!) inside reactors; although apparently leaky coax is a really effective solution to the first)
It's PTC's Vuforia Chalk: https://chalk.vuforia.com/
I have a separate full time job and I'm not totally comfortable with sharing who I work for, my apologies.