China’s economy is on a tear. Factories are humming, and foreign investment is flowing in. Even so, the wealthy and powerful people atop some of the country’s most prominent companies are heading for the exits.The latest are Pan Shiyi and Zhang Xin, the husband-and-wife team that runs Soho China, a property developer known for its blobby, futuristic office buildings. In striking a deal this week to sell a controlling stake to the investment giant Blackstone for as much as $3 billion, Mr. Pan and Ms. Zhang are turning over the company as high-profile entrepreneurs come under public and …
