If having a cheap but modern and capable 6000ton (full displacement) ship is the initial goal of this ship, I wonder wouldn’t just keep on producing and improving 052D be the better choice? I mean yes eventually each unit of 054B will be cheaper than the current cost of each 052D. But considering the development costs of a brand new ship like 054B with its all new electronics and so on, while the more 052D being produced, the cheaper it will get.
Reasons:
#1 - The 054B is a FFG, while the 052D/DG is a DDG. In the PLAN's operational doctrine, DDGs and FFGs specializes in different roles and responsibilities respectively. To put it generally:
1a. The DDGs are tasked with mainly area/fleet-wide AAW and AShW, with secondary role in ASW; whereas
1b. The FFGs are tasked with mainly ASW, with secondary role in mid-range AAW.
Both their roles and responsibilities actually complement each other instead of clashing with each other.
#2 - Upgrades to the radars, sensors, and combat-&-command systems to the 054B significantly enhances its warfighting performance and survivability over the 054A/AG.
#3 - Sooner or later, the 052D/DGs will be succeeded by newer, more capable general-purpose DDG models that are going to be more expensive than the 052D/DGs we have right now. This is a natural progression of technological upgrades and advances on warships (and pretty much many other things, obviously) around the world, of which many people often neglect to consider when discussing matters such as this.
This goes the same for the 055 DDGs which we have discussed previously in this forum.
#4 - Even without #3, increment retrofits and MLUs conducted/to be conducted onto the 052D/DGs will eventually add onto the overall development, construction and upgrade costs of the individual ships. So it really doesn't matter much in the grander scale of things, vis-a-vis how the 054B is going to cost closer to the 052D/DG, etc.