I don't think 058 will be a light destroyer, more like a medium DDG with more VLS cells (80+) and higher displacements (9000+ tons), but that debate is just semantics. No one knows what it will be.
Everything else you've said I agree with. A new dual phase array on top of the mast will really differentiate the 4th batch of 052D from the rest.
I think 80 VLS cells can be achieved with a ship the size of the 052D, i.e. 7500 tons full load. You have to eliminate the VHS array and add another 16 VLS in that position.
I think 9000+ tons is too close to a 055, and you might want to retain the 2 gas turbines instead of 4 to maintain your fuel economy.
My idea is still essentially a 052X sized vessel with a new set of prime movers, the 2 diesel engines replaced by 2 induction motors as prime movers and retaining the two gas turbines, albeit expect that the gas turbines are now 30,000 to 33,000 mw each. At best 8000 tons displacement and not over 9000. Due to the prime mover change, the Type number is changed.
My idea why a 052X sized vessel will be retained, is that PLAN appears satisfied with its configuration and when they are satisfied with something, they tend to go all the way with it. As much as they want technological advancement, the PLAN also seems very conservative in other measures.
To compensate for the removal of the Type 517 VHF array, the main arrays must be strong enough to detect stealth aircraft. This seems to be a tough PLAN requirement. The reason why the 055 isn't sporting an L-band, UHF or VHF array is probably because they are using the brute force method which however requires a lot of juice to the arrays, which contributes the ship's size and a high number of generators. So work will be done on this department.
With the X-band array to complete the dual band, the work will be easier. Removal of the Type 364 surface search radar, the Type 366 antiship radar (also used for OTH purposes), and the Type 344 gunnery fire control radar means we can use the power requirements of these three radars to feed a four panel X-band array that is serves the purpose of all three. The radar will be set high on an integrated mast for the best possible radar horizon. Complete with the removal of the VHF array, we will remove anything that needs to mechanically rotate or steer except for the small navigation radars.
Just above the X-band, we will put a four panel CEC array. The ECM will follow the new style introduced with the 055 which consists of a panel on the side of the superstructure. All this and more, we take the equipment introduced on the 055 and bring them here for a repeat.
The characteristics of the ship should be:
The ship must distinguish itself from the 055. You don't want it fully duplicating the 055's mission, though we can allow for some overlap, and it needs to offer a significant advantage of economy, both in its new building and in its running, than the 055.
The ship must also distinguish itself from the next generation frigate. Again, it must be significantly more capable than the smaller ship.