It was discussed on here a while ago but don't forget that the Perth master plan is predicting growth over the next 10 years with no change in infrastructure. If the airport is at capacity now, who knows how long you will be waiting for in 10 years time.
I think the only good thing a Carbon Tax might do for aviation is put some pressure on the government to actually build some decent aviation infrastructure and services. It will no longer be acceptable to sit in traffic induced holding patterns or be number 28 for takeoff if your fuel burn is being taxed into oblivion.