The MCAS idea has been around for some time apparently. Boeing were going to fit it to the 767 originally, but were able to get the job done with vortex generators. Both the KC-46 and KC-767 have a MCAS system.
https://aviationweek.com/defense/boe...cd1cc979ac68a7
FAA doesn't want to be the first to lift the MAX ban.
https://aviationweek.com/commercial-...cd1cc979ac68a7