I do need to correct myself on "heavyweight torpedoes" being the principle sub weapon. They also carry ASCMS and long range strike weapons.

They are extremely limited however in the use of these weapons because of the limited filed of regard (a sub can only organically attack what it can see with its radar (<20nm) sonar (CZ at ~30nm agianst a noisy surface ship) or ESM (maybe a little longer than sonar, out to at most 50nm if there are good surfce ducts). To use a 200nm anti ship Cruise missile requires third party targeting and submarine strike weapons are limited mostly to fixed shore targets, of things queued by UAVs tlaking back tothe sub.

With the exception of the SSGN (which will be gone in 15 years without replacement) a sub can only muster a salvo about equal to a single aircraft.

Creating a "sea control submarine" is akin to building an SSBN is is currently an option not being considered becasue of the expense - like 10+ billion with weapons and unmanned vehicles. For 2 of those you get a Carrier battlegroup. Withthe Subs you have maybe the firepwer of one War at Sea Strike from the CV, then you need to go back to port and rearm. The carrier can saddle back up and regenerate such strikes, or conduct a cyclic "conveyor belt" of ordnace for long periods.

From a small wars standpoint, the question bolis down to what is it you want aviation assets (manned nad unmanned craft and vehicles) to do for you, and with what periodicity? With that one can look at the cost vs risk of expandable (submarine-based) or regenerative (CV based) assets providing those requirements.