President Xi Jinping has set his sights on a "powerful" currency befitting China's growing stature on the world stage, one that could challenge if not erode the U.S. dollar's decades-long dominance in financial markets. But the Chinese yuan, or renminbi, is unlikely to become a key player in foreign exchange reserves without sweeping structural reforms that Beijing has been hesitant to make, analysts say. Despite lackluster consumer demand and a five-year housing slump, China still is by many