A blockade is an act of war. Were the PRC to act in this manner precipitously, they would find themselves in a very bad spot. The PRC wishes to intimidate and threaten Taiwan and the world into letting them just come in and take over the island. Currently China's economy is the worst of all the developing nations. They lack the GDP to carry on a protracted military campaign and their naval vessels sport mostly 90's and early 2000's technology. Their hope is to take over with Taiwan's technology intact and thus extricate themselves from their economic depression. Predictions aren't worth very much, but mine are that they will engage in cyber-warfare and selective assassination to weaken resistance to their desired goal. Anything more aggressive than that could indicate that Chairman Xi’s impending fall from power.