cannot,
why would they have to park aricraft? If 100% fail command course this year they can extend the 50 or so retirees. Also they can simply work all captains, who are not G day limited, into overtime. If there are say 600 captains, we would all be worked up to 92 hrs...still a lot cheaper using overtime than upgrading CNs! Also, if they anticipate a high failure rate, they could divert any unproductive training to straight line flying...not much of this but it all helps!
Grounding lots of aircraft due failures/training...highly unlikely!