President Trump holds all the cards against Mexico, and they know it. He holds the cards, the chips, the felt table, and the chairs.
Mexico is in many ways like Venezuela. They are both socialist pseudo democracies that depend on oil. Both have lost the ability to produce oil profits from a combination of low prices and years of neglect and corruption.
Mexico is on life support now with income from drugs and remittances, both of which President Trump can cut off. Mexico must negotiate, the only question is what will Trump ask for? He needs to ask for reforms to be implemented within Mexico that will reduce the corruption and increase economic development. If they do this, they will not have to depend on immigrating here.
They could solve both problems just by selling PEMEX to a company like Exxon or even a consortium of companies!. ........
If Trump can make El Corrupto do the right thing for the Mexican people many will go back, few will want to come and the extended Mexican family, the jewel of the Americas, will survive. Real trading partners and win win.
That may be a good approach.
"I'll send US companies down to help you get lots of oil money - none of those anti-oil greenies involved - and you use some of that money to build the wall"...:^)