I bet YYZ's will be next.

I never quite understood the point of the program. In aggregate, it takes just as long to screen a passenger through this vs the regular queue. It doesn't create any additional capacity, nor does it reduce demand. It might shift demand a bit, but there's only so much you can shift when virtually everyone shows up within a limited band of time before their flight. The airport should be able to model demand based on flight schedules and history well enough to figure out how to allocate supply.

Maybe it was just an outlet to offer to the (legitimate) complainers by shifting screening resources away from the non-complainers.

I also thought the long-game was to charge for the service. Nothing sweeter than selling the solution to the problem you created yourself. Maybe airlines refused to play ball because they knew doing so would create another extortion racket instead of fixing the underlying problem of slow security screening.