It’s 2027, and you’re walking down the street, confident you’ll arrive at your destination even though you don’t know where it is. You may not even remember why your device is telling you to go there.

There’s a voice in your ear giving you turn-by-turn directions and, in between, prepping you for this meeting. Oh, right, you’re supposed to be interviewing a dog whisperer for your pet-psychiatry business. You arrive at the coffee shop, look around quizzically, and a woman you don’t recognize approaches. A display only you can...