With the first Attack sub still 15 or more years away the US is already pushing Australia to enter into a deal to develop the next generation of nuclear submarines.
US pushes next-generation nuclear attack submarine development deal for Australia
Republican House of Representatives member Michael Conaway, has launched a resolution calling on the US Department of Defense and Navy to work with "five-eyes" partners Australia, Canada, the UK, and New Zealand on an "international joint-build, cost-sharing program".
Given that the development time for submarines can drag on for decades it probably isn't a bad idea to enter into an agreement with the US and start the process as soon as possible.
Of course there is the issue of nuclear power to contend with but Australia will probably have around 30 years to sell the idea of nuclear submarines.