I noticed that in the guidance message (from my previous post) the date for fixing problems that prevent Enhanced Typesetting has been updated to October 27, 2020.
I am assuming that Amazon is not actually going to hold anyone to that date since they have not announced it publicly as far as I know.
I wonder whether the pandemic caused them to back off on their plan to require Enhanced Typesetting compatibility and if a new firm date will be set eventually.
EDIT: It looks like Amazon is going ahead with the above date. See
Amazon October 2020 File Ingestion Requirement for details.