Repeat after me: there will be no 'strict' border enforcement, and existing illegals will not be deported; in fact, the numbers are going to increase.
Now, rant and rave about defeatism, etc., but the bottom line is that once you come to accept these conditions, you're faced with two choices: play defense and let the invaders dictate the terms, or go on the offense and pull-off a reverse hostile takeover.
All Mexico needs is (1) private property rights, and (2) contract enforcement. Both would come as a result of US federation under our legal system.
Those two things alone would send 100m US citizens south, and somewhere in the vicinty of $5 trillion in capital investment.
Doubling the beautiful Caliornia coastline through Baja alone would generate enough economic activity to employ every man, women & child in the two countries.
"Repeat after me: there will be no 'strict' border enforcement, and existing illegals will not be deported; in fact, the numbers are going to increase. "
You know this how? Seems to me, it isn't over yet. So none of us can say with such certainty what will be.