AIP can certainly cover the NWP that is within Canada's EEZ. You do not need to travel the entire distance from port to port under water. It would seem some 1000miles would be the most difficult part of the NWP. Also, is it essential to sub patrol along the NWP or just at key choke points. Australia doesn't have coverage of the entire Indian and Pacific oceans, its about choke points that traffic goes through.
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Victoria class has AIP? The Victoria class is 70's/80s technology. We may be confusing terminology here.
Japans sub could certainly be an option depending on what Canada is looking for. They are fantastic at deep diving and silent patrols, long high speed transits less so, but still as capable as any European conventional submarine. The LIB endurance, like any new technology is continually improving. Certainly an option.
Not sure I agree that none will get built. Australia has previously built 6 submarines. This has all occurred before. Not just with subs, with essentially every military equipment procurement even ones that went on to have very successful and effective careers. Would you rate the Attack class project below that of Spains S80+? Brazils Álvaro Alberto? Argentina's TR1700? How does it rate to Collins class? Frances Rubis class? UK Astute class? Or Canada's own Victoria Class?
I don't think Australia nor Canada are keen to increase the complexity of submarine building with a joint program. But like the Type 26, you can have unique branches off a common design. However, the Barracuda design would be awfully large, awfully big program to get into.
KSS-III may be ideal for Canada and meet most of their requirements, and give very tangible capabilities. It doesn't have to be a mega project.