"But he has a winning political coalition behind ..."
This claim underlies the entire article. Is it true? Will it be true next week? Next month?
Mexican trade with the US is in surplus, but the important number is the current account, which is a $8 billion deficit. All that trade is being done by US companies and the profits do not stay in Mexico.
 The Mexican peso is down because it has a current account deficit, not because the Mexicans are manipulating their currency.
Like Trump, the author has little or no understanding of trade deals or who wins and who loses through trade deals like NAFTA.
Trump has blundered on the TPP - a huge win for the US that he has abandoned. (A huge loss for Canada that Trump's blundering has saved us from.) Trump will not be allowed to blunder on NAFTA - his support will evaporate before the negotiations end.