The decision to replace Australia's submarines has been stalled for too long by politicians afraid of the bad media about "dud subs" the Collins class got last century.
Collins class subs deserved criticism in the 1990s. They did not meet Royal Australian Navy (RAN) specifications. But in this century, after much effort, they came good. Though they are expensive, Collins class boats have "sunk" US Navy attack submarines, destroyers and aircraft carriers in exercises.
Now that the Collins class is up for replacement, we have an opportunity to reevaluate our requirements and see what technology might meet them. And just as drones are replacing crewed aircraft in many roles, some military thinkers assume the future of naval war will be increasingly autonomous.
The advantages of autonomy in submarines are similar to those of autonomy in aircraft. Taking the pilot out of the plane means you don't have to provide oxygen, worry about g-forces or provide bathrooms and meals for long trips.
Taking 40 sailors and 20 torpedoes out of a submarine will do wonders for its range and stealth. Autonomous submarines could be a far cheaper option to meet the RAN's intelligence, surveillance and reconnaissance (ISR) requirements than crewed submarines.