Just an often overlooked question:
Where are the smaller shipyards in China that western PLA watchers do not regularly visit (i.e. there are no satellite images on a regular basis)?
If there is a plan to change status quo in the next couple of years, one of the critical requirements would be to bulk up the fleets of medium sized amphibious ships. Most of those would be LSM, LST, large LCAC, things like type 072 versions. All those vessel types ranging between a few hundred to a few thousand tonnes, which can easily traverse the 80-200 nm trip.
If the PLA were discreet (I think any well thought out plan would need to be), then any lead time activities would only be taking place at these rarely monitored locations. And we may not find out until a large number of them has been launched. And most of these types of vessels don't need shipyards that focus on ocean going vessels.