China (or any nation for that matter) will never need the capacity to deploy all of it's marines in one go because not all of those marines would be available for deployment all at once.
In addition, I can see the PLAN being more interested in LHDs than LPDs in the long run, and this is an area where I can easily see the PLAN diverging greatly from the US model.
Firstly, unlike the US, China has no reason to need to deploy so many marines so far from home. They do not need to come to Europe's aid to help fight off the Soviet Red Army, and they do not try to be the world's policeman, so no amphibious invasions of Iraq or Afghanistan.
The main reason China is pursuing LPDs is the old adage about better being prepared in having something and not need it rather than getting caught out needing something and not having it. As such, I do not see them needing or wanting anything like as many LPDs as you are suggesting. I would say that between 4 and 6 would be the most I expect the PLAN to have at any one time unless something drastic happens to change that equation.
I do, however, see the PLAN being quite keen on LHDs once they become available, or maybe more precisely, once China has a decent medium weight helo that would make such vessels worthwhile to have for the PLAN.
LHDs would be a lot more flexible for the PLAN, as they would be able to deploy naval Z10s on them, and thus could be used almost like mini aircraft carriers in the same manner as the US Wasp class, only without fixed wing aviation.
Such LHPs would be a lot more practical to deploy to any trouble spots in the SCS or Africa, both in terms of military assets for evacuation or strike purposes, but also for humanitarian relief missions.
Firstly, the PLAN is not going to have anything like as many carriers as the USN, that means that the PLAN would not likely deploy their carriers like the USN does. I can see a minimum or 3 carriers with two being kept close to home waters at all times and one carrier off on patrol somewhere. To help cover the limited carrier numbers, I can see the PLAN deploying lots of LHDs as the flagships for small action groups to maintain a presence in more areas of interest.
I can see the LPDs being mainly kept near China's coast, along with the Liaoning and any future carrier battle groups while LHDs might serve as first responders with small battle groups on 2-4 FFGs and DDGs as escorts. Any such response group would be able to easily handle small crisis like evacuating nationals or limited strikes on anti-government forces or pirates/terrorists as well as provide humanitarian assistance to natural disasters.
If something big happens, that is where the real carriers would come in, and having the LPDs near home would also allow the PLAN the option of loading up a substantial ground element to go with the carriers if so desired.
Based on all of that, I can easily see the PLAN getting just as many LHDs as LPDs, if not more LHDs. So I can see a future fleet of many 4-6 LPDs and maybe another 4-8 LHDs max for the PLAN.
