The great thing about the Monarchy is not the power it has but the power it withholds. Imaging having a presidential election where the candidates were (Sir?) Tony Abbott, Robert Katter, Kevin Rudd, Joseph Hockey or The Puddle? Or maybe Murdoch would become an Australian again so he could be elected by News Limited.
At the moment the idea of a Australian Republic would be suicidal. Our political system is just not robust enough yet. Maybe one day, but if the position of a Head of State became a political position at this stage we would be in real trouble.