AUKUS and the Royal Navy's submarine availability problem

How could AUKUS submarine construction affect Royal Navy commitments?

Shared production could support additional British submarines, but the existing force is too small for all of its global commitments.

Competing demands in the High North, nuclear-deterrent protection, the South Atlantic, and Southeast Asia would stretch the Royal Navy's attack-submarine force. Seven boats cannot sustain all of those stations once maintenance and training are included. The estimate here is that three or four additional submarines would be needed to make the new Pacific commitment credible. A British-built intermediate Astute variant with a new reactor and vertical-launch module could spread development costs with Australia while increasing available Royal Navy hulls.