What our major concern should be is culture-cide.
Rather than America being denuded of citizens, it will be overrun with non-citizens.
Even if there is a Great Depression, there will still be food. The government will find some way to feed people, even if it's only beans and rice and Government Cheese.
The real question will be whether the future populace that just happens to be living in the region commonly referred to as North America is worth giving a care about?
Will we be a nation of freedom loving, God fearing people? Or will we be an uncivilized mob led by a few elitist snobs?
What America will become is a Third World one party socialist shithole.
Neo-Feudalism FTW!