Imagine designing a bicycle without triangles. Every joint needs to be overbuilt, because there's no structure from the geometry. But you make sure it still has a top tube, so its just as hard to mount and dismount as a normal bike. Incredible!
This is the first step to having magnetic wheels become a thing. We know canonically Jim Kirk's motorcycle uses these, so it's definitely mainstream by ~2250.
Honorable mention: the Bell Riots happen September this year, and it seems we're on track for those too
The wheels are apparently really really loud when they are mounted like this. You just can make good enough ball bearings of this size at any reasonable cost and weight
Is there any regime where this is more efficient than spokes? I'd imagine that at high speed there's an aerodynamic advantage (possibly similar to a track/TT disk wheel?), but I can't imagine the bearings being better than current bikes. But bearing loss might (???) just scale linear with speed, so probably a win from aero in the end. But this isn't counting weight, which I imagine is worse (but doesn't matter much at high speed on flat ground).
First, the hold on the rim must be very tight and precise or the wheel will wobble like mad.
Second, such a tight hold will be very sensitive to any kind of dirt, so it has to be sealed.
Any seal tight enough to keep extremely small dirt out will cause loads of friction.
Tight seals in general is not an option, they exist en masse with e.g. hydraulic cylinders. But for them, the friction is basically a non-issue in comparison to the overall power budget. But I cannot imagine an even halfway free wheeling wheel that will not break down after getting in contact with a bit of sand.