It'd be a nice touch, but I'd be worried that once you take out the Aborigines there'd be nothing to do.
Perhaps there will be little happenings in Australia one campaign. But it's important to remember it's an alternate history game, not a straight historical. It may rebel and declare itself an independent country in one campaign, or in another Britain fails at completely colonizing it and other powers stake out pieces of the pie, making it a battleground. Perhaps in another the aborigines civilize, or a rival nation of Britain's decides to put some speedbump's in Britains way by lending the aborignes Krupp cannons, some rifles, and a few modern textbooks.