I feel like they could be great hybrid devices; bicycles and scooters, even ridden slowly, cause too much disruption on sidewalks. A gyro wheel at walking speeds ought to be just fine. (I was just trying to figure out a way to traverse five miles from a light rail stop to my sister out in the suburbs; the streets are often unsafe for cycles, basically no room for anything except for a sidewalk.)
People on gyrowheels can go faster than traffic in urban centers, yet not speeding, they're just coasting along at running speed. Doesn't take space, doesn't add much weight in case of collision, doesn't make the driver feel speeding and not care about pedestrians because he's usually unprotected either. I don't know how efficient they are but I could see this as a regular mode of transportation.
Also wonder how to adapt this for disabled/elders. Something a bit more convenient than an electric wheelchair, a bit leaner. Old people might even have a spot to put a package.
Small-ish electric motorcycles (scooters with a seat). Gyrowheel is definitely not an option for disabled or elderly folks, or even many more abled ones, they rely too much on the user's ability to remain stable and standing.