At this point in mobile technology, I see no reason why an AR D&D game for mobile devices can’t be a thing. Between Pokemon Go and D&D Beyond, there is enough skill and talent to make this a reality.
In my imagination, your phone or device could be both your character sheet and the client for the game. You are given a fantasy map and an overlay like Niantic‘s very popular games. The overlay contains any number of Gaming Worlds (read: Theme Setttings). Supply Locations and Store Features are linked to similar real world locations like Stores and Suppliers using Augmented Reality and GPS. Random Creature encounters happen just like Pokemon Go! You build a Party with Friends or on your own (though I imagine playing with real friends would be totally better).
In terms of adventures, creating campaigns would be possible but most of the World/Settings would be procedurally generated.
And for those that say GPS driven games take you out of the real world (Arguably, the exact point) good manual design could take people to very interesting locations. Add the ability to capture video and upload to “Adventure Journals” and you have memory making and Social sharing.
I know there is a strong opinion that devices and nature clash and should not be mixed. My thinking is that devices are programmable and can be told to push reminders to put them down. Nobody does that, but if you think about it, its the fastest and best way to remind people to be present in the actual moment.
Anyway, I’m calling it now. D&D Adventures driven by mobile technology to get people to go on Real Adventures in the Real World. If someone is already doing this, please point me to it. I would love to see it.