I think they can add a Towed Array without a huge change to the vessel. I think they can replace some of the armament (ie SSMs with ASW missiles) without a huge change and retain the main gun, the HQ-10 missiles and the smaller 30mm guns as well as the helo landing pad in the process.
In fact, I believe the PLAN will have some ASW variants...and, they may go about it in such a way as to not impact the building of the hulls in the least. They could make such a switch over a modular thing that could be conducted in a few days in port if they made the systems (the ASMs vs the ASW missiles, and the sensors associated with them, as well as the Towed Array) modular enough.
Then all the hulls remain essentially the same and they task various vessels within floitillas, or various individual flotillas for the respective duties as required.
I think they could do this with this design...but we shall see.
As it is, as they sit, they are very decent low intensity, multi-role vessels.
056's intended to replace 037 enmass.
037's originally was a sub chaser. but it's family wsa grown to have differnet variants. one of them had Towed Arrays.
all of 037 were intended to operate near eastern coastal seaboard acting as asw patrol screen and littoral gun boats.
so yes 056 will have a asw towed array. but it would not that useful as the acoustics in eastern seaboard don't make for nice areas for towed array. more likely it will use its sonar bulb on active to make life complicted for IJN... I mean JMSDF... diesel subs.