I agree that some may not want to continue working as an instructor, but, at least the airline is trying to do something to help the training schools continue - they are essential to the future of the airlines. If QF does not employ instructors at flying training schools then these instructors will be snapped up by other airlines and as such will be lost to both Qantas and the training schools. This plan is simply an investment in the future for Qantas.
There are a number of pilots in GA who don't want to do the Second Officer role in QF and consequently apply to DJ, JQ, CX etc for First Officer positions. If they are instructors then QF may now be appealing as they can remain instructing (on excellent pay) in their stable domestic environment while their seniority number goes up and then join the airline when a F/O position is coming up. This plan may not suit everyone but I'm sure that there are some who find that it suits their situation.
QF Flight Ops Training have been developing this concept for quite a while now and it's obvious that it is going to cost a lot of money. Management have realised that they have to spend big money to secure enough pilots to fly all the aircraft that they have ordered (knowing this will make the LH EBA quite interesting). Word is, expect an announcement soon that QF will pick up the full cost of pilot training for young school/uni graduates interested in the profession.