But given that it's 10+ DDG hulls that still have good service lives, it seems (to a layman like me) to be a bit short-sighted to not make the extra investment to bring them up to something closer to the new 054B standard instead of the older 054A.
Thanks for all the responses. I will not post any more questions on this topic
If they're going through an MLU, that typically means that they have already gone through half of their service life.
Is it worth the additional cost to bring them up to Type-054B standard, or is it better to use a new hull?
They can run the production lines for the Type-054A sensor and weapons loadout out for a bit longer, given this will be at minimal cost and they'll be stopping production soon anyway.
Remember for ASW work against submarines, you want to use the smallest and least valuable ship you can.