Now that the 054a line is winding up.. Isn't it strange to have no info about the 054b. Is it that there will be a gap in frigate production since no design has been finalised yet, or has PLAN achieved the number of frigates it requires for the time being?
The rumor or "leak" suggests that the 054B is getting a design revision from a hybrid IPS to a full IPS.
I also think they are not in a hurry, with all the frigates and corvettes made. Another note is that older destroyers are getting "demoted" to the 054A level as they are MLU'ed to about the same level --- the Sovs, and maybe the 052B in the near future in addition to the already done 051B. At the same time the original 054s appears to be getting their MLU, and raised to the 054A level. So in addition to the 30 Type 054As, you also have a potential another nine ships that are "054A like" in their AAW defense level.
Another thing I suspect is that the PLAN is also having manning issues. Not enough trained bodies to fill the ships. Still one 'ghost ship' --- brand new 052D in Dalian ready to go and has been sitting there for a while. They will have to prioritize manning all those destroyers that are in the building and fitting queues now, on top of the carriers and the 071s. The 056 production may also soon come to an end, and that can help.