Are the total planned units increased above 26 for 052d class?
Or has there been any formal recognition of a follow on class?
Or will there be hiatus in production line?
Since 25th unit is already being assembled in drydock.
I think that 25 units can be split into two groups:
1. 13 units of 052D and 052D+ carrying Z-9 or Ka-28.
2. 12 units of 052DL carrying ASW versions of Z-18 or Z-20.
My speculation is that the 13 units that accommodates Z-9/Ka-28 will join the existing fleet of 17 modern ships (this means all destroyers excepts the obsolete 051 Luda class; that would be 2 x 052, 1 x 051B, 2 x 052B, 2 x 051C, 4 x Sovremenny, 6 x 052C) to form a group of 30 modern destroyers. These will join the 30 054A frigates to form a 60 ship group. I think these would form what I would consider the 2nd tier force of the PLAN surface fleet.
052DL and 055 will be the 1st tier force, with both accommodates larger ASW helicopters like Z-18 or Z-20. I think they should be group together to form what I would call an ocean cruising force (远洋舰队). These ships will either form task forces with 075 and 071, in a similar way as the USN Expeditionary Strike Group (ESG). Or they could form CSG's with the catapult equipped carriers.
Therefore, I think there should be at least another 4 units of 052DL which makes up a 2:1 ratio of 052DL and 055 (16:8).
In the long run, I think it depends on how 052 series will develop.
If a new 052E ships which excels at both ASW and air defense appears, then I think this new 052E will be produced along side 055A in a 1:1 ratio. I would expect this 052E to have at least 80 VLS cells and have two hangers for ASW Z-18/Z-20. That's pretty much a mini 055.
If the PLAN decide to go the division-of-labor route between air-defense and ASW. I think the current 052DL is good enough, along side an ASW frigate/destroyer that has better propulsion system than the 054's with 2 hangers accommodating ASW Z-18/Z-20.
The 052E route will result in larger ships, less in number, and more expensive per-unit cost. The division-of-labor route will result in smaller ships, more in number, less expensive per-unit-cost. Frankly speaking, I think the 052E route is better. But the division-of-labor route is more suitable to what the PLAN already operates.