Even in a situation loaded with both tragedy and outrage, some irony surfaces. Particularly, it does appear that the aircraft is headed for a return to service. Leaving aside the very specific questions about a third AoA vane or some synthetic substitute, as well as related questions about fine points of handling characteristics, what is one of the outcomes of Boeing's pretty well-documented effort to avoid including pilot training requirements specific to the 737 MAX? There will be pilot training requirements not only as large and extensive as what the company had been trying to avoid but even more extensive, won't there? Especially in light of the added complexity (if that is the right word) imposed by the several reconfigurations or rearrangements of the MCAS (as well as some other systems, if I understood accurately).
As for larger lessons learned, a good guess is that trying to boil down many years of corporate senior management obtuseness (and, it appears, venality) into bite-size and readily understandable lessons is mostly a waste of time. If the history has been told correctly (and that does not mean I am questioning whether it has been told correctly) and one main root of what went wrong is the corporate acquisition of McDonnell Douglas, then what is the lesson to be learned from such a massive misstep? Maybe the answer is "stakeholder capitalism" and a rejection of the Milton Friedman bedrock economic guidance. Yet those are big wrenching changes and so wouldn't help much in the present day with engineers confronted by questionable practices.
Litigation, legal types such as this SLF like to say, has a way of focusing the mind. There's no shortage of lawsuits, on top of multiple U.S. and other countries' inquiry boards. But, "who decides?" What is the decision-making authority for what the lessons truly are? (apropos of safetypee's post above). It seems too clear that the matter of "who decides", at this moment . . . . is just getting improvised. Doesn't there have to be a better way?