It's been a hot topic both inside China and outside on fast China should build its navy fleet and what size it will eventually reach, given the rapid pace that PLAN is building/expanding. The concern is that China is eventually going to slow down and settles for a more steady and sustainable ship build rate and, when that happens, China would be facing a situation where it has a glut of shipbuilding capacity, much of them wasted.
There are two reasons why this worry is both premature and misplaced.
First, for all the talk about China's impressive naval ship construction, China still only has 5 052D's and more 051's than 052C's. It still has not had even a single class of batch-produced world-class SSB's. While all of discussions around 001, 001A and 002 (and 003) are pretty exciting , China still only has one carrier in service, which mostly serves as a training ship. The first domestically-built 001A won't be commissioned until 2019 at the earliest. As it stands, PLAN is not even where it should be for today's China, let alone China in the medium term. It seems that a lot of people are confusing the reality with a projected future, prematurely worrying more about the risk of excess capacity and waste of resources two decades down the road than the risk of not having a navy commensurate with China's strategic needs and national interest before it that happens.
Second, while it is true that building at such a frenetic pace is not sustainable in longer term and can cause idled resources and wasted investment for most countries, it's not entirely applicable to today's China. China does not need to invest more in infrastructure and labor to build naval ships at today's rate or ramp up even more. The capacity is there already. China has plenty of shipbuilding capacity now. it'll be a waste to not fully utilize them now. In fact, one can also argue than a decade or two down the road, it'll be much more expensive.
As to what kind of fleet level that PLAN would want to achieve in medium term (2030 ~ 2035), we don't know exactly since China does not publish a 30-year navy fleet plan or something like that. But it's not too difficult to guesstimate based on what we observe today and on China's strategic requirements in medium term. IMO, it's easier to speculate naval capital ships than tanks or military aircraft. China has two strategic directions that need navy presence and protection: Western Pacific and Indian Ocean (OBOR). There is converging consensus that China needs six aircraft carriers in medium term, plus the corresponding escort fleet. These are the power projection fleet; China also needs homeland defense fleet to take care of SCS, ECS, and Taiwan contingencies (the US, btw, does not really need a homeland defense fleet; Coast Guard will do). Another way to look at it: PLAN is increasingly modeled after USN and it will only be the US that can seriously threaten China's security - it makes sense to benchmark PLAN against USN. It's not unreasonable to believe PLAN will aim at its fleet at about 1/2~2/3 of the USN with similar force structure. Specifically, my speculations are in medium term as defined above, the PLAN will have about 6 carriers, 50~60 modern cruisers/destroyers, 50~60 modern frigates (excluding 056's), 20~30 SSN, 10~12 SSBNs, 8~12 LPDs, 6~8 LHDs as well as other support ships.
It will not surpass USN during the time period, but it would be far and away world's second most powerful navy.