What would that be? I've never understood this either. Because once China takes over Taiwan, it'll become, in a few short years, just like mainland China. And it won't be any different - no better, no worse.
What keeps China on it's knees is it's lack of understanding of how Capitalism works. Money is only the means of keeping track of who's done a favor for who. It's a bookkeeping concept. China doesn't need to sacrifice now for the benefit of future generations (a la Mao) but to start paying their workers enough so each can "buy their own Model T. Ford".
Until they "get that" concept they'll be the slave labor workforce for the world.
Not that I totally object to getting well-made, inexpensive products -- a great short term benefit -- but it's a short term benefit that's mucking up the world in the long run...
What would that be?
Beijing's inferiority complex. The very existence of Taiwan as a prosperous free Chinese society is an insult to the ChiComs' whole ideology, and they just can't tolerate that. That's all this is about.