Purpose for invasion
I think maybe it’s appropriate to remind what the discussion is about.
Taiwan represents the government of China as recognized by the Allied powers after WW2. It has historical legitimacy albeit not a realistic one given PRC's standing.
Declaration of independence by Taiwan would therefore acknowledge defeat and remove any claims to the government of China as a whole. Independence would also legitimize PRC as a government of China, and therefore the original Communist revolution.
On the other hand the Communist Government claims legitimacy to governing China based on the revolution. Taiwan is part of China and therefore it harbours a regime which is anti-revolutionary, and would not be pronouncing independence but in fact secession, which is a form of counter-revolution under PRC’s constitution (and in fact would be in most countries.
The big problem is that PRC is rapidly approaching a state of society that can be said to be ‘Yugoslavianized’ in that its society and economy are evolving to a model approximating market economies, while its political culture remains Communist, albeit of an increasingly pragmatic nature.
Taipei does have options, but none are very acceptable politically speaking.
It can wait, as mentioned by eckherl, since significant change takes time. Usually significant social change takes 60-80 years (3-4 generations).
In modern times China was induced into change by the Europeans from 1820s, transforming from monarchy to republic at the turn of the 20th century. Even as the republican era dawned, the form of that republic was already being challenged, and the end of this era culminated rather neatly just after the end of the Cold war with renewed commitment by the Communist government to further economic development, and accepting social change that this would bring to its society. Next time to change will not come until 2060s at the earliest.
Waiting another generation (20 years – c.2015) may bring the political culture more in line with the rest of society, or it may not. One of the problems is that the social transformation is economy based rather then based in legislation based as happened in Europe. The economic transformation is to a significant degree dependant on the resources of the state and in particular the Armed Forces…which are a significant part of the party political culture. The Armed forces anywhere are not democratic institutions, so they are usually the last to accept social changes that require greater liberalism, hence the spate of coup de etats that accompany social transformations. However the Armed Forces derive their personnel from less developed parts of society that fail to aspire to greater material achievement (commonly urban). This is the much larger and still impoverished rural population, so the ‘reset’ may in fact be retrogressive towards greater Communist ideal of more equitable redistribution of resources by the state, or the New Cultural Revolution.
Waiting a bit longer (40 years – c.2035) may bring a new popular hero to the fore, for which there are many previous precedents in China’s history. Usually this would be a ‘righteous general’, but invariably this would cause a fragmentation of China. This would be a highly motivated individual born about 10 years ago, and hence raised in a China unlike that of Mao. What would China of 2035 be like? Probably quite socially fractured, and not unlike many military-based regimes of 1970s Asian countries (Marcos Philippines).
Now the purpose for PRC invasion is to remove opposition to it's regime from what it sees as an entity within it's sphere of governance. However Taiwan may become the catalyst of change PRC fears so much. Hong Kong is already providing just such an effect on China, but it is small by comparison, and is somewhat of a desensitizing agnt of change in a very large population. Taiwan would be a much larger 'drop' in the proverbial China tea cup.