The People's Bank of China didn't take to Twitter to troll Donald Trump and Hillary Clinton. It used an old-school reserve ratio cut to spite those critical of Beijing's currency policies.

The yuan, make no mistake, is headed lower, not matter what Chinese officials said at the recent Group of 20 gathering in Shanghai. The only questions are magnitude, when and how? Does President Xi Jinping plan to engineer the 10 percent to 15 percent devaluation many expect all at once, or in drip, drip, drip fashion that roils them for months to come?

Yes, much to discuss at the annual National People's Congress from Saturday to March 15. What should really worry Trump, Clinton and other U.S. presidential wannabes, though, is how Xi has decisively shifted from reform to stimulus mode. It means that China may, at least on paper, get close to this year's 6.5 percent target, but it could imperil the global economy in 2017, when a President Clinton or a President Trump enters the oval office.