This from the Wall Street Journal yesterday on the likely response in the onshore yuan (and the People's Bank of China setting of it):
"If the U.S. goes ahead with tariffs, China would need to consider some of the more aggressive options," said Brad Setser, a senior fellow at the Council on Foreign Relations. "Letting the yuan weaken becomes something that logically the Chinese would consider."
Brad Setser nailed it! …. this today:
Past few months for the onshore yuan …. weaker against the dollar