What you read is called the Chengdu Secret Treaty, a secret agreement between the two communist parties in 1990. Since it was not published, all speculation was speculative, I hope what many people still say in 2010 will not happen.
However, this modern era is unlikely to be invaded by force. China may become "colonist" or "fascist" in a different way.
In my opinion with the Hong Kong problem: It is a long-term war because it is difficult for China to make concessions, because if it makes concessions, it will create "precedents". And China cannot because it will have problems with Taiwan, Inner Mongolia, Tibet, etc. Interestingly, the fall often occurs under the domino effect. :) Too bad I found that is happening in Hong Kong has little impact on the morale of a small fraction of Vietnamese.
It is great that you are interested in the developments in Vietnam @joeyarnoldvn :)
RE: Blogger Pham Doan Trang Receives Award For Work to Improve Journalistic Freedom