I might be biased, but I really think it would be a natural next addition to Animal Kingdom. With so many ecosystems and unique wildlife, it would have been a great fit that could lend itself to both rides and animal exhibits. It's also one in the current climate that they could do and with minimal care avoid any controversy about cultural appropriation, etc. To keep this vaguely on topic, I'm less convinced Australia would be a great addition to World Showcase as I don't think it would really add anything particularly unique in terms of architecture or culture.
My impression, though, was that it has never had much support internally and, more specifically, that Australia/New Zealand was not somewhere that particularly sparked Joe Rhode's imagination. Now with the IP mandate, I doubt we'll get any more "real world" lands at Animal Kingdom for the foreseeable future.