FTA: “5G networks will be able to use the round-trip time from a single tower to locate a device. That’s because massive MIMO and beamforming allow 5G towers to send precise signals directly to devices”
That could make face identification a lot easier and more reliable. Instead of matching against a database of everyone in the cell tower’s range, it could match against faces known to be in sight.
And yes, the thought of phone providers knowing the fairly precise location of all their subscribers’ phones (and smart watches, and cars, and smart TVs, and fridges, etc) all the time scares me, too.
I don't see what 5g brings to this application. This could be a offline application with a one time face/profile database. More probably it would be released as offline face detection, upload face images to the cloud to match and get profiles. 5G has better dataspeeds, but uploading cropped faces over LTE would be fine.
Maybe you could use it more reliably at the ballpark where there's enough density to justify deploying base stations in the new high frequency / low range spectrum.