In response to Grampa Jim's July 23, 2023 post:
I think the extreme Australian and US investment in making Virginias for Australia a reality would make Australia more of an essential ally for the US.
ie. Australia would be more the essential ally in peacetime, conventional wartime and even in a nuclear war. This might work to overide isolationist trends in US politics.Also emerging hypersonic missile technology could make Australian Virginias small but critical platforms that could carry nuclear tipped hypersonic missiles to deter China. Submarines are the best means of nuclear deterrence. I would call these Australian subs "Submarines Hypersonic Missile Nuclear propelled (SSHNs)."
Conventional subs like Japan's Taigeis (and indeed the Collins) are of declining value in Australia's Indonesian Archipelago Straits and South China Sea critical mission areas. This is because China's fixed and mobile anti-submarine acoustic sensors are becoming more effective in detecting when conventional subs run their diesels in those areas.
Also such conventional subs are too slow to combat the more capable Chinese navy, air and rocket forces.
I think if Australia is unwillling to turn to submarine nuclear weapons then after the Collins life extension (LOTEs) keep Collins going through to the late 2030s, XLUUVs or XL-AUVs are Australia's submarine future. These XLUUVs include the RAN's Anduril GHOST SHARK project.