Scruff,
Quite possible you're right with this.
But I don't have enough intel on the backend of the test to comment. But what you say sounds about right.
Qatar won't dis honor a contract solely based on the adapt.
But I'm certain that upgrades/transitions will be asked to take the test. And with good reason I'm sure.
As for new hires, the airline can always find ways for the employee to take the test in a non jeopordy atmosphere.
But too little intel on the matter to comment.
Cheers.