If all the Sovs get refurbished with AJK-16 VLS, then the Shtil missiles can only be given to 052Bs. If the 052Bs also get refitted with AJK-16/UVLS, there are no other vessels in the PLAN that can host Shtils. Is the PLAN going to just leave them to waste or schedule enough live-fire exercises to them all up before hauling the ships in for MLU?
I would also wager the 055, after entering service, would be the PLAN's most potent ASW platform due to its voluminous bow sonar, dual hangar, and UVLS.
Yes, the Shtils would go to waste, just like all the electronics aboard the Sovs along with the Sunburns, etc. If the PLAN is willing to ditch the Sunburn in favor of the YJ-12, I don't see any reason they wouldn't also be ok with ditching the Shtil in favor of the HHQ-16.
As for the 055's ASW capabilities, yes they would be in aggregate greater than a repurposed 168, but they would certainly not be used in main or perhaps even at all for this role unless in the worst non-ideal circumstances. I am referring to a PLAN surface combatant primarily intended for ASW, like the 054A+, for example. Pretty much all modern warships are multirole, but some ships are better at some roles than others. 052D and 055 are unquestionably primarily AAW but could obviously do ASW in a pinch. The legacy PLAN destroyers cannot easily mount the UVLS system or the radars that would be needed to guide LRSAMs, so they are effectively going to be defaulted into ASW.
Given the PLAN's historical lack of naval air strike, it has always had "distributed lethality" in its fleet structure with all PLAN surface combatants having decent to excellent ASuW capabilities. There are other roles of course like land attack, anti-sat and ballistic missile attack/defense, and AAW command, but these are easily going to be primarily or even exclusively the 055's domain. So basically for each of the PLAN's ships it comes down to a question of ASW + local (medium-range) AAW + ASuW, or fleet (long-range) AAW + backup ASW + ASuW. To the former category will belong all of the PLAN's present and future frigates as well as all the refitted legacy destroyers, possibly including the 051Cs (depends on what they do with the Rif-M complexes). Of the former category a refitted 168/169 in the manner I described would certainly turn it into the most potent primarily ASW platform in the PLAN's inventory. To the latter category will belong the 052C/D, the 055, and all future destroyers/cruisers.