The purpose of the subs is not to attack Taiwan, but to attack our carriers in deep water. China is preparing to go to war with the USA. It is also why they are getting carriers. Carriers to Taiwan is foolish, land is an unsinkable carrier in that case. Carriers are for forward force projection. Like protection of an invasion fleet.
But since Clintoon fired most of the real Navy Officers and put in perfumed princes in high places, it seems there are no tacticians left.
Umm,Subs have a very important & definite purpose as far as Taiwan is concerned in ensuring a economic & military blockade of the island which will lead to tension with the US in one way or the other.China's 1st carriers will probably not hit the waters till around 2010,by when India,Japan & even Australia all will have 1 or more carriers.China will need atleast 5-6 carriers(& not to forget the accompanying escort & logistical units) to even think of taking on the USN & that is atleast 15 years away.Till then,the PLAN will be trying to browbeat Japan & also try to disprove the notion that the Indian ocean is not India's ocean.