Fact of the matter is that Qantas put in a massive order for A320's recently, these were all convertible to A321's and A319's. A good proportion of them were earmarked to go to the premium carrier that Qantas at the time was going to set up in Asia. Now that venture is dead in the water, Jetstar has already got the number of new aircraft on order that are required for the expansion plans.
Qantas may as well deploy the remainder in Australia. Talk of the C-series being a better fit is largely irrelevant due to the orders already being placed. The A319 is a top machine and perfect for domestic ops. Easyjet up until 2 - 3 years ago only had the A319 as the A320 didn't make commercial sense.
Why not deploy them to Qantaslink, they can be sold to the airline as the shiny new jet for the crew to gain experience in return for accepting a contract below Qantas mainline and even possibly below the Jetstar EBA. The pilot group will accept it as we come over all 'giddy' when offered a new type on the licence, long term thinking doesn't come into it. Before we know it we will have a new 'bottom' level for Jet pilots in Australia and Qantas can continue to re-build its domestic premium network at a much lower cost base.