Just a few points
I'd say CEC for a destroyer is a must-have these days.
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It goes back to why would you want an arsenal ship.
CEC itself should not be taken as a silver bullet for everything. What happens if you have EW aircraft involved trying to jam or interfere with your links? It becomes useless. So does you arsenal ship. You go back to the reason why its better to have self contained fire control systems.
In addition to this, the Arsenal ship will need its own close range defenses. CIWS, short ranged missiles like HQ-10 and the like. Your costs go up along with sensor systems that need to support them. You will need at least a Type 364 radar or equivalent.
For the 1st Island Chain, shore-based missiles work out better for cost and survivability.
But for the 2nd Island Chain, the distances are too far from mainland China (1500+ KM), so missile cost and flight times go up dramatically.
So it makes sense to sortie missile carrying platforms closer to the targets in the 2nd Island China.
But a Chinese SAG approaching the 2nd Island Chain (which is beyond the range of most air/missile support from mainland China) is a risky proposition.
So most of the Chinese destroyer VLS cells would be loaded out with SAMs for defence, with only a few VLS cells available for antiship or land-attack.
So a SAG would be be dashing in to deliver a missile strike, then rapidly withdrawing.
That argues for a fairly powerful surface group with at least 4 destroyers for air defence.
And for arsenal ships able to keep with such a SAG.
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China can be expected to build a fleet of 50+ multi-role destroyers (Type-52D and Type-55)
That is enough to cover the entire wartime mission set with at least a few destroyers in every surface group.
So building a subclass of say 6 arsenal ships is justified, because those ships will always have a role in complementing the destroyers.
Primarily by carrying lots of missiles, but also offering additional ASW helicopter support like a frigate.
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I see a better need for an even larger surface combatant, but not an arsenal ship. There is a difference between the two. Maybe something more akin to what the USN is proposing as the LSC or Large Surface Combatant.
This will even include a new VLS design.
A Type-71 is cheaper than a destroyer yes.
But is it fast enough to keep up with Destroyers on a dash to the 2nd Island Chain?
Nor is a Type-71 built to the same standards as a Destroyer. Remember that it is facing the same threat level as the other ships.
Plus a Type-71 could have 250+ VLS cells, which does seem like too much risk and cost in a single ship.
Why does the Arsenal Ship need to keep up with the destroyer? Its more the other way around. Some arsenal ship concepts are centered around converting existing commercial ships.
Indeed that is why an arsenal ship comes with hidden costs. Among which is deploying frigates and destroyers dedicated to protect it.
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Also the words "expendable and multi-role" don't go really go together in warship.
Tell that to every modern frigate.
Multi-role means more capabilities and higher cost, along with fewer numbers.
Expendable means fewer capabilities and lower cost.
Not necessarily as modern frigates have shown. Look at the versatility of the 054A versus destroyers of the older generation, 051B, 052B, 051C, Sovs.
An expendable arsenal ship would look like a faster version of a Makassar LPD with say 80 VLS cells, costing say $150M?
Why would an arsenal ship have only 80 VLS? That's not an arsenal ship. If you want a ship with only 80 VLS you might as well make a destroyer.
What I see is larger combatants are becoming the trend. Frigates are now the size of cruisers in WW2, destroyers are becoming cruiser sized. After some years, the 055 may not look so big after all, and there maybe bigger surface combatants as part of this trend.
I don't see building more 056 like ships in the future, unless the PLAN goes to the Russian route of building corvettes with a few large anti ship missiles.
Setting the bar is like working on a sliding bar scale. You have to know where exactly you want to slide the bar in the middle between the two extreme ends.
I still see the need for a frigate, which can be defined as the smaller size that you can make and cost, and still be regarded as fully ocean going, blue water, capable of carrier escort, is capable of ASW, ASuW and AAW operations. It may not be the best in AAW operations versus a destroyer or a dedicated AAW vessel, but it should still have a respectable and potent capability of it, even if diminished compared to larger ships.
This is followed by an upper tier where you can have dedicated AAW ships, or ships that can contain enough VLS for everything else.
Naval history lesson has shown you do not neglect the importance of the Escort. They do most of the fighting and dying like they did in WW2. Of course, our idea of the Escort keeps going bigger and bigger, and in fact the 055 can be considered an escort. If mega ship trends continue, we will see larger and larger surface combatants. But not necessarily arsenal ships.
