You may not care, but it certainly seems that immigrants care. Why do you suppose Europe is being flooded with non-Europeans? America was for hundreds of years de-facto Europe.Yes they can. If they want to stay together. One of this nations best resource is its children. I dont care what skin tint they come with, just make sure they know what it took to create this nation and what it takes to keep it.
The demographics, culture, enabled similar societies to be built - ones that I'll argue cultivated more progress in a couple hundred years while other areas with dissimilar cultures carried on as they had for millennia.
If we commit racial suicide and lose our uniqueness as a people do you really think we will continue to enjoy our unique amount of success as a society? What does the evidence show thus far?
My wife and I both have Indian blood. The culture was strong with my dad's side, even stronger in my wife's family. The history of our families is a fine example of what happens to a culture once the demographics tip to a different group. You lose your language, property, system of government, and eventually are assimilated into whatever the prevailing mass has become. I'm not arguing that Indian society was better overall, nor am I attempting to play the victim/oppressor game. It's just a mathematical fact, and history proves it over and over again.
So which culture is worth protecting? Which systems have the best opportunities?