Just fine the employers and they will go home on their own. And if it takes 1 trillion dollars to deport the rest, so be it.
And...add this: WHY should the Mexicans work for cheap? Why should they be the next slave labor group? They should be insulted, and want to come back legally for a decent wage. grrrrh! It's the soft bigotry of low expectations...hmm...now WHERE have I heard THAT phrase before??? /sarc