Australia has too many dioceses - as should be clear to Blind Freddy, most of the country dioceses are unviable, having small populations, hardly any priests, few prospects of local vocations, and a general dearth of talent. I suspect that the reason that several of them have remained vacant for over a year after their bishops retired is that no one offered them is willing to take them. As should be obvious, the number of priests worthy to be made bishops now and in the future is very small, given the poor quality of Australian clergy, and this simply compounds the problem.
For a start, Sale diocese is only viable because two-thirds of its population reside in the burgeoning south-east suburbs of greater Melbourne: since the people there are in every sense Melburnians, it is ridiculous to have them look to Sale in Gippsland. Better to reamalgamate Sale with Melbourne, and soon enough merge Ballaarat and Sandhurst (Bendigo) with Melbourne as well. As for Hobart - after the retirement of its current incumbent - it can easily be run from Melbourne via a fax machine, as a number of priests once told me.
If in any of these dioceses there were oodles of practising Catholics, and a supply of home-grown vocations, of course they would be viable: but there aren't, so they're not.
For similar reasons, Adelaide should have Port Pirie given back to it; and Perth should retake Geraldton and Bunbury, while Broome could be given to Darwin (better still, the latter pair, by reason of their remoteness, should be downgraded to Apostolic Vicariates).
Now, I don't know much about Queensland, apart from it lacking any faithful priests or bishops apparently! - but, since it is more decentralized than other States, I assume that it needs more than one diocese (Brisbane).
In New South Wales, that dreadful and badly run diocese of Broken Bay should be merged back into Sydney forthwith. However, beyond that I don't really know; some of the country dioceses are doing alright (e.g. Wagga Wagga, those in New England), while Wollongong, being in essence a city diocese, I assume is large enough to be self-supporting. All agree that Wilcannia-Forbes and several of its neighbours won't last much longer, though: and these should be merged with other dioceses forthwith. Why waste time?