Yet another way to get a handle on the integration issue is to look at other pairs of nations with a long history of interrelating and shared culture. Take Germany and Austria. Ireland and the UK. The US and Canada. The US and UK. Australia and New Zealand. Ukraine and Russia. Taiwan and Japan. All these represent nations with shared cultures and languages, close trading relationships, colonial histories, and so on. Some of them are far more economically interdependent than China and Taiwan. Yet no one ever argues that New Zealand and Australia or Germany and Austria will become one state because they are so economically and culturally interdependent.
Update:The Madman of Chu responds here.