“The crazy thing is, that the engine companies could have developed electronic engine controls for their current engines, making them perfectly capable of operating on unleaded fuel; long ago.”
This is not really true. Aerosance/Continental tried it with what became the PowerLink system. Aerosance’s intent was to eliminate the need for 100-octane by manipulating timing to control detonation. They couldn’t make it work. Lycoming tried with the IE2 system. Similar results. The engine still needs 100-octane.
One reason, I was told, is that acoustic knock sensors don’t work well enough on these engines to respond quickly to detected knock. Also certification challenges.