I’ve never heard of the idea that Australia might be an island instead of a continent. Grew up in the 90’s in the US, FWIW. I wonder if “Australia as a continent” is an older idea?

Of course people will argue endlessly about what exactly a continent is (can’t just use geology because then Europeans don’t get to be special), but the truth of the matter is, capturing Australia gets you +2 troops in Risk so it must be a continent.