If one gets into the weeds of the whole messy thing, the Shanghai Communique acknowledges the position of both sides (Taiwan and China) that there is one China, the 1982 Joint Communique acknowledged the Chinese position and said the US had no intention of pursuing a "two Chinas" or "one China and Taiwan" policy. And of course there's a non stop stream of such political speak, which is a red herring for the whole issue. Beyond minor changes to wordings, the main things the US did that screwed over Taiwan:
1) Revoking the mutual defense treaty which legally bound the US to defend Taiwan, replacing it with a more vague law where military intervention was not clear.
2) Recognizing the PRC as the legitimate representative of China.
To align your claims slightly, Taiwan also claims the same section of the SCS (actually it claims a slightly larger part), so strictly speaking it is what happens if the "Chinese claims" are realised (Taiwan and China work jointly to support their claims, ironically enough). In real terms the economic effects of China with respect to the SCS are greatly exaggerated for a number of reasons. First being that shipping can be routed through Indonesia. It is not a chokepoint, it just happens to be the shortest route. Second, blockades have little to do with recognising swaths of ocean as territory. These are enforced by navies, and most blockades in history have not happened within the blockaders' own waters (for obvious reasons). It is no easier for China to blockade trade in the region if it claims the SCS. And third, of all the major economic powers, China has historically been the least likely to enact economic warfare like blockades or sanctions. There is also a fourth aspect where in the current political environment, the globalised, trade based economic order is the least popular in the US and assorted European states, not China (who in fact desperately needs trade).
1) Revoking the mutual defense treaty which legally bound the US to defend Taiwan, replacing it with a more vague law where military intervention was not clear. 2) Recognizing the PRC as the legitimate representative of China.
To align your claims slightly, Taiwan also claims the same section of the SCS (actually it claims a slightly larger part), so strictly speaking it is what happens if the "Chinese claims" are realised (Taiwan and China work jointly to support their claims, ironically enough). In real terms the economic effects of China with respect to the SCS are greatly exaggerated for a number of reasons. First being that shipping can be routed through Indonesia. It is not a chokepoint, it just happens to be the shortest route. Second, blockades have little to do with recognising swaths of ocean as territory. These are enforced by navies, and most blockades in history have not happened within the blockaders' own waters (for obvious reasons). It is no easier for China to blockade trade in the region if it claims the SCS. And third, of all the major economic powers, China has historically been the least likely to enact economic warfare like blockades or sanctions. There is also a fourth aspect where in the current political environment, the globalised, trade based economic order is the least popular in the US and assorted European states, not China (who in fact desperately needs trade).