Qiu Huiying, a human resources manager in Guangdong, worries in numerical terms when she looks ahead to the next decade: a 20-year mortgage, a 10 per cent loss on her property and thousands of yuan in monthly childcare costs that are set to rise.She bought a 624 sq ft flat last year, so her mother-in-law could move in and help care for her son. But the purchase now feels less prudent after prices in the 20-year-old complex have already fallen by about 10 per cent.Like many urban households in...