This seems to be "tombstone" learning..
LionAir didn't know about MCAS, so plain stuffed it up.
Ethiopian learnt about MCAS due Lionair, but didn't know about next to impossible trim forces and yoyo, so stuffed it up.
So airline #3 will come along; know about MCAS, know about high trim loads, but will then encounter ???
It's a rum way to do airline safety... I know in IT we used to do field tests to let customers shake out the bugs but I didn't know aircraft manufacturers now practised it..
G