Realistically speaking, how many SSBNs and SSNs could the PLAN muster in the Western Pacific as of current?
Due to the extreme secrecy of the PLAN regarding their submarine forces, any feasible number regarding China's nuclear-powered submarine fleet is very hard to come by, even by estimates.
Either way, according to
@5unrise (i.e. Eurasian Naval Insight), China currently has around 9-12 SSNs and 7-8 SSBNs.
Although realistically speaking, only the 093 SSNs and her variations (093A and 093B/G SSNs) should be counted for operations deep into the Western Pacific. This is because the 091 SSNs is pretty old and very loud, which diminishes their stealthiness greatly and severely compromising their capabilities in fighting against opponents with strong ASW capabilities, i.e. JMSDF and USN.
I choose not to count the Type 032 SSB, because she would most likely be a minor factor in case of a hot war in the Western Pacific.
Furthermore, any reliable estimates on the number of nuclear-powered submarines that China can build per year?
Moreover, is there any plan to have another shipyard to expand China's nuclear-powered submarine fleet?
I believe the key to securing China's future dominance in the Western Pacific would also require a credible underwater presence with greater endurance capabilities to act against the navies of the US and her allies in the region. This demands a sizeable nuclear-powered submarine fleet for the PLAN, and having only Bohai to pump out nuclear-powered submarines seems kind of risky to me.
(As a reference, on average, the US can build 1 SSBN and 2-3 SSNs per year across 3 (now 2) seperate American shipyards)