The Australian government report is 20 years old, with the public seeing it via Freedom of Information laws. The science hasn’t changed. The report warns about serious implications of lower fertility rates.
After saying that a fertility rate of 1.65 would lead to a stable population (zero growth or loss), because of the rates of immigration…
“In contrast to the outcomes if the population stabilised at around 24 million, if our fertility rate were to fall much below 1.6 there could be serious economic and public financing implications. This is a plausible possibility,” the department warned.
The news article doesn’t elaborate, and the actual papers are not available online yet. I would love to see the details around serious economic implications. It looks like the papers are called [Standing Committee on Ageing Inquiry into long term strategies to address the ageing of Australian population over the next 40 years]