Retail apartment buyers in China only borrow half the capital from the banks, but the developers who build them borrow all of the money from the bank, interest-free, based on their "guanxi" relationships with bankers. So instead of reducing prices on unsold apartments, popping a bubble, they and the banks collude to just let the empty apartment buildings sit there empty for years, until they sell. The property bubble might not burst for a long time.

Of course there's also social pressure on young unmarried males to buy apartments, because the girls won't marry them if they don't. I predict the banks will slowly lower the capital requirements, down to 30%, then 20%, then 5%, eventually to 0%. After that will come a Chinese version of CDO's, then, perhaps decades later, the bubble will burst.