Current Shanghai, Beijing housing market is the 金圆券 printed by the local government and realtor. People with money will lose money by inflation. They want to invest but have no other place to invest except the 金圆券, In order to continue the game year after year, the local government will push the price up and up even if it could be against the interest of the central government.
Secondly as the RMB appreciating, foreign capital wants to take the ride too by buying realtor assets.
As the RMB peaks, say 5:1, foreign capitcal will take profit. That will drive down the RE price. Yet the key factor is if China will become a free capital flow country. If it will, the Chinese people will even trash their RE and by US treasury bond.