The Taiwanese still expect to hold out fighting the mainlanders for up to a month in the case of a landing. Also only approx 10% of the Taiwanese coastline is really suitable for establishing beach heads, it means the defenders' job is rather simplified.
The Taiwan Strait also isn't actually that narrow. It's comparable to the width of the Baltic Sea, and considering the opportunities for planning how to stop a Soviet amphib invasion at the height of the Cold War done there, Taiwan has all manner of opportunities to make it a very hard proposition for China.
The Taiwanese defense doctrine these days also emphasizes asymmetrical measures to as much as possible hurt and degrade Chinese amphibious capabilities before reaching the island in case of an invasion attempt. Consequently the real investments have been in air force, navy, and general air defense and naval strike capabilities. (Chinese airborne forces are not of the numbers that China can hope to invade using air assault alone, and so needs to come by see.) Stopping as much as necessary to make a Chinese landing attempt unworkable is all Taiwan needs to do to defeat an outright invasion.
It seems one of the critical issues for Taiwan is whether they can acquire, or themselves learn to build, a credible number of modern submarines.
Taiwan’s Indigenous Submarine to Be Based on European Design
China can still blockade and starve them of course.
most of your information is incorrect.
in 2007, it is being asked to the head of defense in taiwan island, how long time taiwan island could resist in case of PLA attack, the answer is 2 weeks, and all others depend on US actions.
in 2007, mainland do not have any 054A, 052D ships, let along J20 planes or carriers. and remember it was 2 weeks (which is exaggerated by taiwan military anyway), so NOW, it becomes A MONTH? that is a joke.
and "Indigenous Submarine to Be Based on European Design" is a further joke.
if you read a little more, you will find the medias in taiwan had questioned for a long time, that the "European Design" company is just a shell company which claimed to be in Gibraltar. further report exposed that the company is actual controlled by some taiwan guys.
Indigenous Submarine had already been a shame chapter to be ignored in taiwan medias, yet you still brought it up here.