Can China with probably the world's most powerful and centralised government absorb Hong Kong where people live by self reliance under a minimalist government? Will China truly follow the idea of one country, two systems and and allow Hong Kong to function as it has until now? Coming from Canada, I am aware of the consequences of such a system.
Canada, which exists as one country, two systems, has struggled with large minorities seeking greater self-determination.
In Quebec there has even been an attempt at complete separation. One of the reasons Quebec has not separated is that it has always been an integral part of Canada. Without Quebec, Canada would probably not exist. In reply to my second question, I doubt if in the political arena, China wants two systems in one country. Uniting Hong Kong and China will be a difficult process.
Fortunately, the Chinese majority of Hong Kong and the people of China share a long history, but for many people this is overshadowed by more recent memories of people leaving China for a better life in Hong Kong. Those who found it have strong feelings about the place where they have become successful. In their hearts, they are Hong Kongese first and Chinese second. The Chinese from the mainland, who do not know the ways of Hong Kong will face many obstacles. It is inevitable, in the near future at least, for China and Hong Kong to remain separate even though, officially, they are one country.
If PRC leaders force their polices and practices upon Hong Kong without adopting many of the policies and attitudes that have made Hong Kong so successful, they may succeed in bringing about a rapid integration of Hong Kong into greater China, but at a cost of alienating local people. As the former Soviet Union found, alienated people quickly discover their national identity when a government can no longer restrain them. Unless China empowers its people with greater freedom and fair representation it will likely discover it has sown the seeds of dissent which will lead to the break-up of the country. This is what happened in Latvia, Estonia and Lithuania.
I do not think economic autonomy will threaten the greater unity of China, since regional taxation and spending policies do not directly alter a person's identification with the larger country.