Given that each state was a self governing colony before federation, it would be almost impossible for Australia to be a unitary state at foundation, as the colonies would've been very reluctant to give up so much power, so federation probably wouldn't have occurred.
Post federation this may have been possible, perhaps the Commonwealth extends its powers during the Great Depression or WWII.
Every now and then there is discussion about the waste and duplication of the different levels of government, so while it is a long shot, it could still happen in the future.
Given that each state was a self governing colony before federation, it would be almost impossible for Australia to be a unitary state at foundation, as the colonies would've been very reluctant to give up so much power, so federation probably wouldn't have occurred.
and even that, especially post 1994, has had quasi federalism at timesThat's not necessarily an issue. South Africa was a unitary state when it was formed in 1910, and it was made up of four self-governing colonies.