Maybe that's today's policy tomorrow maybe different, although I dont hold out much hope for the current shortlisters.
QF have had a policy in place to reduce the number of permanent staff against contract, part-time and casual for some time now and that is up for review again at the end of the financial year.
4-5 years sounds a bit drastic considering there are provisions in place to ensure the ratio between permanent and "others" doesnt exceed a certain %, therefore I dont think even QF HR could predict 4-5 years down the track just yet, however I am sure this is what QF would love (no permanent employment) I think it will be difficult to achieve just yet.