Do you think those who wish to come north will simply throw their arms up in defeat and relegate themselves to the life they have currently?. None of them will get into boats and go across the north Gulf coast?If they're so darn motivated and ingenious then why haven't they improved their situation at home?
I know it sounds all romantic and all to pit human spirit against a structure but the plain facts are that walls work - they work everyday.
Mexico has a two tier caste system. The few who have, who own all and control all, including the oil pesos, and the remainder. Those on the bottom have nothing. It is easier for them (currently) to attempt a border crossing, than to lay down their life (a certainty) in an attempt to change the mexican current system. Perhaps if the price of coming north is more costly, and less fruitful, they may well take up arms, and stage a ling overdue revolution...a real one.
In the long run, that is exactly what it is going to take, for those south of the border to have a real life, where they live.