If that is ultimately the conclusion, then it still gives the FAA and EASA a black eye, since they allowed the aircraft update without additional training for MCAS.

Best case scenario for Boeing is that the Ethiopian Airlines crash turns out to be something else. If it is MCAS related Boeing, the FAA, and EASA amongst others that green-lit the update without training have a lot to answer for.

Here's the thing. The additional training is not strictly necessary. The same procedures pilots are already trained for in previous models should have saved the aircraft. Unless investigations turn up a new problem.

Of course, one could argue that, by disclosure changes to the system, that the pilots would be able to react faster. But that's not really for us to decide.