Aragonite - LookML validation issue

[skpadgett]

Developing in project on release 22.8.32 with Legacy LookML enabled (Aragonite setting).  When team member switched setting to default (Aragonite enabled), developers in project were no longer able to validate LookML, getting error below.  

Errors out of date. Click the test button to validate your most recently saved LookML.

Changing setting back to non-default/Legacy enabled.  Error went away.  Concerned about what will happen when the ability to enable Legacy is deprecated in future release.

Any guidance?