Whether there will be a new class to replace type 052D or rather the latest variant 052DG is a bit premature. The first 052D was commissioned only 5 years ago, and the first 052DG is not yet in service. Construction of type 052DG or newer variants will continue to around 2024/2025.
052DG has lengthened stern helicopter deck, and new anti-stealth radar. There are some upgrade in sensors not readily visible on the outside.
If there is a class of successor to type 052DG, it will be a completely new design with larger displacement and new futuristic weapons (laser/rail gun), new sensors and new propulsion system ( all electric?), and probably appear around 2030.
Meanwhile type 055 will continue to be built, rumour has it that the orders from PLAN has increased to 12 ships, up from original 8 ships.
Personally, I would like to see a future PLAN fleet make up of >10,000 tons destroyers, >6,000 tons frigates and >2,500 tons corvettes, which mean there will be no new DDG in same weight class as type 052D. But that is just my personal opinion.