How long the "Bubble" will keep?

After I read MR. Ren Zhiqiang's ( CEO of Hua Yuan real estate company) speech, there is one question always in my mind: how long the bubble in Chinese housing market can keep? Because of the traditions, Chinese people tend to buy at least one house. There have been an ad said, " No house, No family". After 1998, the price of Chinese housing market increase rapidly and still increasing. " Fueled by low interest rates, prices in Shanghai and Beijing doubled in less than four years, then doubled again ", Washington Post Staff Writer Steven Mufson wrote the news " In China, fear of a real estate bubble". Compare with the wage level of Chinese people, the house prices are extremely high, some Chinese people joked that we are the slaves of house. It is sure there is bubble in Chinese housing market and the government also try to use some policies to slow down the growth of house price, however, Ren Zhiqiang said every Chinese should buy houses a few days ago to encourage more people invested in housing market. From the other side, most Chinese believe that the house price will still go up, so they are stretching to pay prices at the edge of their means or beyond. It is dangerous for Chinese development.

If we leave the example and assume people will still believe the growth of the prices, never change their mind, how long the bubble can keep? and why it break?