When will China overtake the U.S. to become the world’s biggest economy?

Few questions are more consequential, whether it’s for executives wondering where long-term profits will come from, investors weighing the dollar’s status as global reserve currency or generals strategizing over geopolitical flashpoints.

In Beijing, where they have just been celebrating the 100th anniversary of the Chinese Communist Party, leaders are doing their best to present the baton-change as imminent and inevitable. "The Chinese nation,” President Xi Jinping said last week, "is marching toward a great rejuvenation at an unstoppable pace.”