It's quite clear that AA has the capability to make this hit fast and hard when it thinks it is to its advantage and can get away with it.

I have little doubt that AA would consider this kind of change to be to its advantage if the other US majors lead the way in making such a drastic change or follow AA in doing such a drastic thing.

By now, all of AA's "competitors" have been given plenty of indication by AA that AA has ready capabilities to make the switch to charging YQ on partner award tickets and that AA has some willingness to do so (as with AA doing so on award tickets involving BA flights). DL also has signaled to others what its capability is and that it too has some willingness to go on this course. After UA (and/or US) reveals some such capability and willingness, then we'll sooner see a deep dive into copying this rather awful aspect of the European majors' programs.