It would be rather ironic for Australia to go from what is often considered a mini-America in the eastern pacific region to a country that vehemently rejects anything even remotely American out of fear of subversion. Of course, Australia thinking of itself as a fortress state isn't exactly anything novel by OTL standards. With Australia's vast mineral wealth and strategic location I'd see them as becoming the subject of heavy investment; particularly as Australia is a largely safe area to get that precious Uranium from. New Zealand probably continues its long, storied history of geopolitical irrelevance though
In WW2 though I'm wondering if Japan would try pressing any harder against Australia than it did OTL. To my knowledge trying to actually invade Australia beyond seizing some of the northern coast towns was regarded even by the IJA to be a dumb idea, but pinning Australian resources down does put allied operations in the area in jeopardy.