You could bet a million dollars that QF WILL lower fares to what the opposition is offering, and people will still fly QF to keep their FF points rolling on.
When the new carriers are then not supported, they pull out because they have no choice - and then the prices will go back up to what they were, or higher. Unfortunately it's the way the cycle goes at places like this.
Although this might change when the E Jets roll into WA on a permanent basis, supported by a FF program, and connections to over East etc.
Time will tell.
(its about now I expect Capn Bloggs to come in with a "bring it on" type of challenge)