Nothing new, drive shaft bikes have been tried and built over here many years ago.
Kirstin who once posted frequently on here had a Sussex shaft drive bike for commuting.
Drive shaft probably makes sense on that sort of bike; I suspect that the motor will mostly be doing most of the work, so inefficiency in the transmission of the human power is relatively unimportant.
I don't think I'd enjoy riding it if the motor failed or the battery ran out (but that's true of our Motus too).