Scenario:
I have a subtype on the ASSET_CLASS field in a table.

When ASSET_CLASS = 3, then the ACTIVITY field uses an ACTIVITY_ROAD domain.
If I were to change the ASSET_CLASS value from ROADS to WATERCOURSE:

Then the ACTIVITY's value would stay the same (although it now shows the domain's code (RWID) instead of the domain description (ROAD WIDENING)...but I suppose that's to be expected).
It seems like ArcGIS should do something to account for the fact that the ACTIVITY is no longer valid for the ASSET_CLASS subtype. In other words, RWID (ROAD WIDENING) isn't a valid ACTIVITY for WATERCOURSE. WATERCOURSE has it's own domain: ACTIVITY_WATERCOURSE.
Note: I did get the message/option below. But choosing "Yes" had no effect on the ACTIVITY field, since the ACTIVITY field doesn't have a default value (and we don't want it to have a default value):

Could Pro be enhanced to account for the invalid domain value in that scenario?
To be honest, I'm not sure what the mechanism should be/how it should be handled. Maybe the ACTIVITY field should get automatically nulled-out? Or a warning message? Thoughts anyone?