[AmVess]

You can seal the bearings, but that cuts efficiency. That's not the only problem, though. The interface between the bearing and the bearing sprocket will make it rather unusable in very dirty conditions.

Their setup seems like an answer to a question no one was asking.

[rhinoceraptor]

The gains you could get from improving drivetrain efficiency are very marginal. Everyone else is working on improving aerodynamics. That's the actual limiting factor in cycling, and it always has been.