I'm just gonna get this out of the way; while I'd love to see Australia represented, I'd feel very uncomfortable making a civ out of Australian history, what with the thousands of years that it was home to a plethora of Aboriginal nations, until the Brits got inand systematically murdered them. As a 'nation', Australia is very young, having only federated in 1901. In additIon to this, there is still no Australian head of state due to still being a part of the British Commonwealth, which makes the choice of leaders a handful of vaguely inspiring Prime Ministers. (That said, I'd totally play a civ run by Bob Hawke.) We also don't have much in the way of unique options, though I suppose like, a Convict Worker would be possible. The closest thing we have to an iconic UU would be Bushrangers, who actively worked against the 'civ'.
All in all, I just don't think Australia (or any Commonwealth nation really, sorry Canada) should be included, both due to historical concerns and simply not making the game any better. Check back in 10 years, maybe we'll be a republic by then.
Our South East Asian neighbors have much more of a vibrant national identity, and I'd be very happy with a khmer and vietnam civ. I'm not too worried about crossover, having played one awkward and confusing game where I owned both Istanbul and Constantinople at the same time. Gran Colombia and Argentina also seem like good options to add in some south american representation, though I feel like a civ like the Nazca would be a lot more interesting rather than two Industrial era nations.
Are you seriously saying you might change your mind about the merits of Australia as an in game civ if Real Australia was to become a republic?
I will bite my tongue on the rest for fear of starting an argument except to say that almost every civ in the game, including our vibrant blameless non-threatening exotics the Viets - who conquered and settled the whole southern half of their country at the expense of the Cham and others - committed gross acts of cultural insensitivity at some point in their history. http://upload.wikimedia.org/wikipedia/commons/8/84/Nam_Tien.PNG
Life was tough once.