The Australian Liberal Party has proposed an "Autonomous undersea warfare capability for Australia's navy" as part of its electoral platform (5 May 2022). Unlike many political promises, this is a very detailed proposal for the Defence Department and the company Anduril. Interestingly the Australian arm of the company was formed only a month ago, and the parent company in 2017, and appears to have limited experience building large long endurance robot submarines.
The proposed submarines would be eXtra Large Autonomous Underwater Uninhabited Vehicles (XLAUVs). These are the size of crewed mini submarines used in WWII, and can cross an ocean, thus suited to operation in Australia's large maritime region. Unlike smaller torpedo sized AUVs, the XLAUVs can't be launched from a submarine, and would normally be supported by a specially fitted out submarine tender vessel. However some US nuclear submarines have the capability to carry an external cargo, and may be able to transport a XLAUV covertly to its launch point. The XLAUV may in turn launcher smaller AUVs, and UAVs, as well as conventional torpedoes, mines, and missiles.
XLAUVs are conceptually similar to the Boeing MQ-28 Ghost Bat UAV aircraft being developed for the RAAF. The ADF would need to develop tactics and train personnel for operating this equipment and learn how to use it effectively, at the same time it is developed. Support personnel, and equipment would also be required. In the case of the XLAUV surface ships would need to be acquired, built, or adapted in support. Oil industry support ships, which the RAN now has two of, may prove useful in this role. Australian designed fast ferries could also be used to deploy and replenish the robots.
If development proceeds well, the XLAUV may render the proposed Australian nuclear submarines obsolete even before they are ordered. The XLAUVs would be superior in the surveillance role to a nuclear submarine, being more stealthy. They would also be superior to deny large ocean areas via the threat of attack. They would not be able to provide as heavy conventional salvo attack as a larger submarine, however, that is not a role Australia is likely to require. In geopolitical terms XLAUVs may have an advantage by not appearing as threatening as large nuclear submarines, while actually being militarily more useful. Australia could support and supplement the robot submarines with a small number of conventionally powered, crewed boats, such as the Korean KSS-III.