More improvements were possible.
1. Less cluttered observation windows.
2. UVLS.
3. IEP.
4. Smaller cleaner gun turret with no built in ladders.
5. Sharp LO bow.
Don't conflate your own preferences with what is either necessary nor "possible".
Three of these (1, 4, 5) are just aesthetic preferences, and really there's no manner in which we can say that the current configuration is better than some alternative (the bow and windows seem fine to me as they are, and even 055's main gun has built in ladders).
2 and 3 are more material changes but whether they were "possible" or not is a whole other story. Being "possible" with more money (either unit cost, or production cost or other) is one thing, whether it is sensible at the service level is another, and the opportunity cost isn't really something we can garner at this point.
Now I think it is pretty safe to say that the PLAN’s ambitions for 054B is pretty limited. The service simply wants a 054A armed with AESA radars and more efficient processors of battlefield information.
Eh,.
The sensor suite and combat management suite of 054B should be something like a generation and a half if not two generations ahead of 054A.
Even retaining the H/AJK-16 VLS -- keeping in mind it is fairly well sized to begin with and could very well grow in cell length -- the above is a huge uplift in capability compared to 054A's sensor and CMS suite. One only needs to look at how much work and improvement in capability the Flight III Burkes had over Flight IIA by having a new radar and related improvements to support said SPY-6, and the 054B to 054A is a way bigger improvement than that.
In terms of the configuration of 054B's sensor suite and especially its primary MFR, it may actually be fairly top of the line in terms of array size and placement.
Even ignoring the sensor and CMS suite, the other benefits of a larger hull with better seakeeping and better crew facilities should not be understated, not to mention likely endurance/range.
Thus, the primary role of the new frigate remains short-to-medium air defense (via HHQ-16C/F) and ASB (I will be shocked if the 054B do not have towed sonars). Anti-surface warfare and land attack missions would be reserved for 055s and 052Ds. As for 054B, the only issue is how to reduce CODAD’s noice in order to maximize ASW capabilities. It is still possible that the population is combined-diesel-electric and diesel (a more advanced form of CODAD)
, which would lead to reduce noice and higher fuel efficiency.
054B should be well into the medium to long range AAW role with its sensor suite and the HHQ-16 derivatives (present and future) it should be able to accommodate.
As for towed sonars, we already have confirmation of 054B's towed VDS door, and one of the other many doors is likely to be for its linear TAS.