I guess that the Priority Award will pull seats from the inventory of the deeply discounted fare in the respective class. This should make it easier to obtain an award seat.
One would hope so!
So I wonder if it would work like the GUP/PUPs - for example, I just used a voucher recently and upgraded a Q to J. (I have previously paid for deep discounted business class fares that are still coded J.)
Another possibility is that your name will be bumped to the top of the waiting list of the normal award inventory, increasing the chance of clearing the waitlist.
Are waitlists that hard to clear in practice? I've only had very limited experience - albeit as TG Gold - LHR-BKK and BKK-LHR clearing within a couple of days of requesting.