DENVER: Chinese seniors are using travel to review overseas retirement options. With UN data showing the number of mainlanders older than 65 projected to almost double to 210 million by 2030, the country’s retirement system would struggle to keep up, especially as the one-child policy limits the number of working-age people who can pay for the pensions and meagre benefits of their eleders, said Yong Cai, an assistant sociology professor at…