I’ve lived in Australia for 15 years. Around 7 of those years as a naturist. I moved back to NZ 5 years ago.
From what I could see, it didn’t look like naturism was declining nor growing. To be brutally honest, my personal observation is that naturism often appears to be dominated by those 40 and older, with higher percentages 60 and older.
That isn’t to say there aren’t younger people involved. It was merely my observation that those I knew through ANF, met at nude venues and the like typically fell into those older age groups.
Two big challenges I encountered in Australia were quite conservative views. The other challenge was the law where nudity is illegal. Australia has no human bill of rights written into law. In territories like ACT that do have a human bill of rights, it’s completely symbolic, because federal law overrides it.
States like Queensland are really anti-nudity. NSW has a few clothing optional beaches and venues. It seemed way more relaxed there. ACT had fairly liberal views on a lot of fronts. One of the first states (from memory) to legalise gay marriage for example.
The other states and territories I can’t speak to.
We toured Australia for about 3 weeks in 2004. We were in Cairns in northern Queensland and were staying over for a few days. My wife had booked a private birding guide and I was going to have a morning free so I asked the owner of the B&B where the nearest nude beach was. She pointed out in the direction of the major beach in the town and said, "Go to that entrance and go left or right for 100 meters and you are there!" She implied that no one would care what I did. I followed her directions and found that she was exactly right--no one gave me a second glance and I had a very nice quiet morning on the beach.
Another time we were in NZ and I was on my own for a week and spent the time divided between two naturist resorts: Kati-Kati and Wai-Natur. Kati-Kati has since been sold by Peter & Joan but is still a nudist place while Kaye and Brian have retired and sold their holdings at Wai-Natur. I think it no longer is nudist oriented. These two experiences in a small country, compared to the USA, were delightful and I found myself wishing that my state had similar opportunities.