Which mid drive motors use the same frame interface?

Question

One concern with mid drive e-bikes is that if the motor breaks in ten years, probably there is no exact replacement available. But do the manufacturers keep the same interface for their different motor models? For example can all/several Bosch motors fit the same frame? I assume e.g. a Shimano motor certainly won't fit a frame made for a Bosch motor? Are retrofit kits the only ones where the frame is not specific for one single motor model?

Which leads to the question: Did someone make a compatibility chart of which motors are interchangeable?

Answer 1

There have been a series of questions about e-bikes component availability/serviceability recently: What characterizes a future-proof ebike drive system? and How servicable are older e-bikes?

There is no standard at this stage, so it's entirely up to the components manufacturers. None of them publish information about mounting points (or statements about compatibilities or long term support), there is no way to provide a "proven answer".

Judging by how bike manufacturers spec the bikes, it may be safe to assume that units from the same manufacturers and the same generation use the same mounting point, but not much more.