BNEA320,
The QF group has ordered WAY too many A320s, and given the performance of Jetstar overseas, they will never need them all, so rather than the expense of cancelling the options,as against retraining costs, makes sense for Qantas to start replacing the oldest 738s with A320 NEOs in due course!
However as Signatures says, its makes heaps of sense, thus probably wont happen!