They will become unemployable. Why would anyone choose to employ someone who can't speak English at the same cost as people who can? There just aren't that many clinically insane contractors out there. So the new citizens and guest workers will find themselves unemployed and the crews will find a new batch of post amnesty illegals to do the same thing, for the same promise of citizenship if they just break enough laws.
I have my doubts. They will still work for less just not as little as they were under the table. In other words still putting the drive in driving down the wages. The main problem we have is that no matter what deal they get it will probably still be better than the one the would get back in Mexico. Most will fight to stay here until they have sucked the last penny they can out of the system.
I firmly believe most of them will have to be physically removed from this Country. Until we have a government that is prepared to do that, the illegals aren't going anywhere.
A good first step is making sure they are cut off from the welfare and making sure those that employ them spend time in jail.