Have you seen what Bridgestone is unveiling for the 2020 Olympics? The tech isn't all that new, but using it as advertisement suggests that models for the public might actually be in the pipeline.
That bike on the photo actually looks like it uses roller brakes.I'm concerned about rotational force on the "webbing" under acceleration and especially braking. Looks like you would need to run rim brakes. Otherwise, squeeze the lever, the hub stops spinning, and a few seconds/minutes later the rubber stops.
Well actually from the photos you can see that it has roller brakes on both wheels. That thing that looks like a U-brake is a dutch style lock.I know, roller front, ubrake rear. And I'm concerned. Remind me not to ride one this summer when I'm not at the Olympics