I think an arsenal submarine makes sense. The payload fraction of ballistic/cruse missiles goes from roughly 20% -> 10% -> 5% for ranges of 1600km, 5000km, 10000km. A 5000km range missile on a moving platform is awkward as the total operational cost of a platform plus the munition for payload delivered at range would be similar cost for a 10000km range ballistic/cruise in a silo/TEL, which can hit anywhere relevant in the world from China. For a conventional warhead a moving platform with a shorter range missile makes sense.
A low cost nuclear submarine built to the 20/80 principal focusing on payload delivered to cost ratio with cheap sensors, low crew numbers and reasonable sound levels would be effective and also increase the effectiveness of the navy's other weapon platforms. The key Idea of an arsenal submarine compared to a SSGN is operating as a team. A carrier battle group with 1 aircraft carrier, 4 destroyers, 2 frigates, 2 attack submarines will have their individual capabilities improved by the addition of an arsenal submarine. The destroyers can remove any cruise/ballistic missiles from their VLS and focus entirely on air and missile defense, the attack submarines can likewise also remove their cruise/ballistic missiles they can also forgo VLS tubes and instead dedicate more internal volume to torpedoes. The attack submarines and frigates will keep the carrier battle group safe from other submarines and the aircraft carrier's fighters will keep the air clear from ASW, from this safe bubble sat 2000km from shore the arsenal submarine can move up 1000-1300 km to the shore and launch it's weapons.
From the rumors in this thread i sketched out a design of arsenal submarine based on the typhoon class submarine, at 1.5 billion dollars this should have lower cost per VLS than attritable unmanned small vessels: