I do not think that China's ascendancy will be peaceful and I'd be glad if time were to prove me wrong. The dangerous period is predicted to be around 2020-25. At that time Europe will have much bigger problems with her unassimilated Muslim population. It's likely the Western world will be preoccupied with Europe at that time. A cocky China will smell an opportunity to enlarge her sphere (like Japan in the 30s and 40s).
Another possible trigger for China could be a recession. Remember, China has had a growing economy for the past quarter century. Most Chinese have never experienced a recession. In the US during a recession, one gets around 3-4 million Americans who're affected and thus unemployed. In a Chinese downturn the number of people out of a job could be over 20 million. I've a hunch that China will suffer a huge downturn; one can support failing state "businesses" for only so long.
I don't think China would be content with gobbling up Taiwan. The mixture of political tyranny and a relatively liberal economy has been quite noxious. The modern Chinese system can be described in one word: fascist. Add a strong dose of nationalism, and we get a monster.
Again, I hope I am wrong. But as the situation in Europe deteriorates and the relative strength of China increases, I just can't see the Chinese regime not flex its muscles. Consequences be damned.
Speaking of political tyranny, read what Foreign Dispatches has to say.