I really don't think you want to put AShBM in something like a 3600t mini nuke.
The South Korean KSS-III is about the same size and equipped with VLS. The smaller Type 212CD is reportedly capable of integrating a VLS as well.
The Dakar submarines that the Israeli Navy currently have on order from TKMS, are expected to be equipped with VLS too, though no idea yet if it's going to be fitted into the hull or the sail. Granted, Israel might be pursuing more of a
strategic capability given their "unique circumstances."
Even the Indian Navy's P-75I program appears preferential towards VLS equipped bids.
I agree with you that there are obstacles to and potential tradeoffs in integrating VLS onto relatively smaller platforms.
However, considering recent developments, a VLS equipped "mini nuke SSK" in the 3,500 ton ballpark is
not implausible and would arguably align with prevailing trends.
Anytime you launch missiles from a sub, it has to come up to periscope depth to do it, which reduces its stealth.
Modern SLBMs are definitely launchable below periscope depth, so if anything, whether a PLAN submarine will have to be at periscope depth to launch missiles will really depend on how far the PLAN has progressed in terms of subsurface communications technology.
It's one thing for 093B to do it, because it's in the middle of Pacific Ocean and has the speed to scoot away afterward. And no other assets can really deliver missiles against San Diego. You don't get the same rationale for a sub that's just operating within 2IC.
The PLAN has yet to secure the 1C, otherwise Taiwan and the South China Sea would not even make for particularly contestable matters.
While the PLAN is definitely sailing a lot further from Chinese shores these days than even a decade ago, 093Bs are not going to be within striking range of San Diego on a
regular basis until the PLAN first secures the 1IC.
How is the PLAN supposed to focus on San Diego when there are more pressing threats closer to home?
Point is
if a 093B can make use of VLS cells in waters closer to home that are currently prioritized by the PLAN, so can a "mini nuke SSK," especially given its probable advantages over "more conventional" SSK platforms in terms of speed and endurance.
