I can only guess as to what the consequences of this will be.

I know that there is this perception that the USA is somehow unique in that it can supposedly function and prosper even if it lacks the homogenous population that is usually required for a successful nation state. And I think this idea comes from the fact that it was historically populated by a lot of different ethnic groups.

Of course it is usually pointed out that the Germans or the Irish were once regarded in much the same way as Hispanics are nowadays. But I think that was different... those groups were so similar to the typical white American in terms of culture, religion, and at a more base level, even appearance.

With Hispanics, integration might not be so easy. Although crucially, they are at least part of the Christian world, which goes a long way to helping them fit it, as the experience of Europe with Muslims shows.

But don't think the USA is untouchable in terms of its territorial or cultural integrity. If you fill a country with third world people you are going to get third world problems. I suppose a lot will hinge on how well those born to 1st generation Mexican immigrants integrate.