China already has Hong Kong, the Brits gave it back to them quite a few years ago. Only it was under semi-autonomous rule. The commies are simply imposing their will on them.
Taiwan is a bit different. China claims ownership of them and says they are a runaway province and not their own country. That's going to be a flashpoint for many years to come. As of right now, there's no real working arrangement for Taiwan like there has been with Hong Kong.
Iran? Screw them and their terroristic ways. I can't think of too many examples where a sovereign country that is bound and determined to get nukes has been stopped by anything other than military force. Let's face it, we've never wanted China, Russia, Pakistan, India or North Korea to have nukes...and they have all managed to get them. For a while Germany, Japan, Iraq, and Libya wanted them. Guess how they were stopped?