G'day and
I'm in Queensland.
I think the biggest threat to breeds in Australia is the import restrictions; just recently we had a few thousand rare breed chickens imported that were culled for carrying Salmonella, even though almost all were clear of it. We've already got Salmonella here. That just boggles the mind, what a waste, and of rare genes too.
If you look into the history of Australia many of our breeds are very inbred because few were imported to start with, and then import restrictions or bans were implemented rapidly and that doesn't leave a lot of options.
There are some great breeders out there, doing their bit for rare breeds, but lack of public awareness is one big hurdle to overcome. Chronic inbreeding is probably best managed by forging links to every purebred breeder, but people are doing that.
While I support the idea of roosters and chickens responsibly kept in suburbia, roosters like to make noise. When someone comes up with a safe control for that, councils could be more easily persuaded to allow chickens.
My mongrel flock, I've realized, contains many rare breed samples. They were mongrelized before I got them but someone, somewhere down the track, or many someones more likely, had some rare and unusual breeds which later someones mixed apparently at random. Still, you can get heritage birds in Australia, of all domestic species we've got.
Best wishes.