Once China becomes a true global power, long term far sea operation is going to be a much more important feature and unfortunately is something you cannot simply just "add" to a ship like weapons or sensors.
Today, the Chinese military is significantly smaller than the US Navy, and would almost certainly lose in a contest for sea control beyond the 2IC.
So the priority is to change the military balance as fast as reasonably possible.
I reckon it will be about 10 years before the overall Chinese military has the capacity to obtain air-sea superiority over the 2IC.
And then another 5-10 years before the Chinese Navy (centred around aircraft carriers) becomes significantly larger than the US Navy, and therefore can credibly operate beyond the 2IC.
That is 15-20 years where the primary mission (for all Chinese Navy ships) will be within 2IC distances, and where the priority is to have the maximum number of high-end ships (such as Destroyers) immediately available in the Western Pacific, not to have them all conducting long-term far seas operations like the US Navy with its obsession on being "present" everywhere on the planet.
And remember that if the Chinese military can establish air-sea superiority over the 2IC, it likely means a significant portion of the US Navy has been taken out. At this point, it could mean the Chinese Navy being larger than the US Navy. The implication is that the Chinese Navy can now roam the seas.
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Remember that they used to send Destroyers on the anti-piracy missions to the Gulf of Aden, but such missions have been downgraded, with even the older Type-053 Frigates being sent. I wouldn't be surprised if the missions were downgraded even further with coast guard ships being sent, which can still do the same job.
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I'm not against a new hull design which is larger, but I think the priority is still missions within the 2IC.
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Can you credibly describe scenarios where a Type-052D needs to conduct long-term far sea operations, and also what weapons or sensors it needs to add in the future, in order to avoid obsolescence?
These hulls are just not built with that in mind as they were originally designed decades ago when China was still weak and sustained blue water operations are a pipedream. The last 052D are likely going to serve into the 2060s if going by a 30 year lifespan or even further into the future if they continue building more of them. While I agree that their weapon system and sensors as of right now are probably going to keep them relevant for a decade or likely more depending how much USN shipbuilding deteriorate, their hulls are definitely not.
VLS cells will still be relevant in 30 years time. After all, you can put any sort of missile in them.
The large AESA radar panels will also still be able to provide long-range air-defence against aircraft and incoming missiles.
Why do you think the Type-052D will only be relevant for the next 10 years?
