Without political reform, writes the China scholar David Shambaugh in his new book “China’s Future,” the economic overhauls that China is embarked upon will stall and the overall economy will stagnate – although not collapse. What are the prospects for such liberalization?

Mr. Shambaugh offers a bleak assessment of China under President Xi Jinping: an atmosphere of repression worse than at any time since the 1989 Tiananmen Square massacre, the elite ready to flee en masse, society waiting to ignite. He says that Mr. Xi’s grab...