We lived in PMQs in Borden until last June, and they were far from full. About 1/3 to 1/2 were empty, based on the unshovelled driveways, and emergency lights that were hanging in the front windows. A friend was told that they had no more two-bedrooms, only three BRs, and all she was entitled to was a 2, so she was out of luck. I personally could see about 7 empty 3 BRs from my kitchen window.
If you're a married/CL person, you should be able to get a 3 BR. My friend was single, hence only entitled to a 2.
But yeah, the PAT situation is a tough slog. From what I heard, most of the married folks managed to eventually get their families to Borden if they wanted. Seemed like every second person I met in the Qs was the spouse of a student at CFSATE!