A social revolution will soon transform China, and multinationals that do business there can’t afford to ignore it. So far, they have mostly focused on the country’s tiny minority of urban-affluent consumers. But as more Chinese migrate to the cities for higher-paying work, they are steadily climbing the income ladder. By 2011, McKinsey research suggests, China should have a lower middle class of 290 million people; by 2025, the upper middle class will be 520 million strong, with staggering disposable wealth. For many multinationals, this is the market of the future.