The 022s use friction stir type welding with its special aluminum composition. This is an advanced form of welding, and having a number of yards do that across the breadth of the Chinese coast is quite an achievement. You don't have a lot of shipyards around the world doing FSW.
As for large ships and nuclear submarines, the real limit is not imposed by production capability, but rather once they're made, where are you going to put them? Nuclear submarines for example, there isn't that many places you can put them in China. Just by looking at the available bases, caves and piers, you can make a good theoritical estimate to the maximum number of nuclear submarines the PLAN can hold.
Ditto with the larger ships, including DDGs, LPDs, etc,. China can support a lot more smaller ships because there are way more places to dock and service them.
As for expecting newer DDGs, lets hope to see more photographs coming from the new Jiangnan yard, not just aerial shots from airliners, but hopefully within. Although I don't encourage someone to actually do it and do things that would otherwise be unlawful inside China.