Perhaps the issue of non-nuclear US subs isn't dead:
The U.S. Navy continues to entertain an internal debate over the issue of just how effective non-nuclear submarines would be in wartime, and whether the U.S. should buy some of these non-nuclear boats itself. This radical proposal is based on two compelling factors. First, the U.S. Navy may not get enough money to maintain a force of 40-50 SSNs (attack subs.) Second, the quietness of modern diesel-electric boats puts nuclear subs at a serious disadvantage, especially in coastal waters.
I know that in general we need larger ships and subs to simply travel the large distances from the continental United States to potential war theaters. Nuclear submarines fit this vision well. But why can't we forward deploy conventional, advanced submarines in potential theaters? Fly the crews in to subs home ported overseas.
Why not home port conventional subs in Guam, Japan, Australia, and Italy, where they can serve in the Mediterranean and western Pacific? And deploy conventional submarines in the Caribbean Sea to free up our nuclear boats for deploying to distant stations when we surge our fleet in an emergency?
I think our conventional boats should be bigger than the European-style boats that reach their patrol stations shortly after leaving home port, but conventional subs have a place in our arsenal.
There is nothing radical about the idea.