Taiwan IS a country and has been since WW2 (technically before too, though it was a lot bigger). There are lots of idiotic regimes that say otherwise, including in my own country. But in contrast to just about every other country on the list, the Taiwanese government has never been conquered and Taiwan has never conceded/accepted PRC rule. It's also fishy that a country is preparing an invasion of its own territory. What is this, the "Obama invading Texas strategy" (lol)?
PRC claiming Taiwan is part of its land is like USA claiming that Cuba is US territory. Even if a large number of nations were to nod that Cuba is now US clay, Cuba would still have its government and would still not actually be part of the USA. Unless the US took it militarily, which would make the world seem an even darker place than it does now.