I feel quite the opposite. 21 new nuclear subs in just 6-7 years completed? Highly skeptical. But we'll see.
Here's my own take on the matter.
If the claimed "21x SSN + SSBN" figure (by 2030, that is) is anywhere near accurate, then according to the 14FYP (2021-2025) warship construction plan for the PLAN previously alleged by pop3, there would be ~11x SSNs + SSBNs launched for that period. Assuming similar rates of nuclear submarine construction by Huludao going forward, that leaves ~10x more to be built within the 15FYP (2026-2030), which should be reasonable.
Though, given the present and near-future geopolitical situations in the IndoPac, I do believe that the PLA CMC will procure more and more advanced SSNs towards the end of this decade, as these
underwater bayonets are especially crucial for China's war effort in a hypothetical Pacific War 2.0.
Alongside the recently-completed expansion of newer and larger submarine construction facilities at Huludao, followed by the gradual spool-up of the construction speed & capacity in the coming years (as the expansion of qualified shipyard worker pool comes into play), I do believe that we would see Huludao launching more nuclear-powered submarines every year for the coming years.
One more thing, though - What I should've mentioned clearly WRT to my "18/21 nuke subs by 2023 is very likely an underestimate" claim in the above post is that this should also take the
"mini-nuke" SSNs into account, which I have provided
. These "mini-nuke" SSNs are expected to be constructed at Jiangnan and Wuchang instead of Huludao, and should allow greater numbers of them to be procured quicker than the larger, proper SS(G)Ns, i.e. 093/A/B and 095.
Hence, adding to previous "XX SSNs & SSBNs launched" claim, the total number of Chinese nuclear-powered submarines to be launched by 2030 is most likely to be greater than just 21.