I am not at all sure that I understand what you mean. Are you talking about race or culture. Whites are not in danger of becoming a racial minority. We are in danger of losing our culture because we are not demanding English be declared the national language and as a requirement for citizenship. That’s it. No more mixed salad culture. Revive the melting pot.
Multi-culturalism is the slippery slope to the downfall of our country.
http://www.guardian.co.uk/uk/2000/sep/03/race.world1
http://afp.google.com/article/ALeqM5h9uOoP7gdbzjvieNt9ZTbgTS4m-g
http://www.indiaenews.com/america/20080212/97236.htm
You are correct that multi-culturalism is killing us, but that's inevitable when you have nation that is very diverse. The assertion that the U.S. has traditionally been a melting pot has some merit, but it fails to note that almost all of those people who “melted” into our society came from Europe. Groups that didn't come from Europe were either small in numbers to the point that they lacked political clout (Asians), or were put on reservations (Native Americans), or were enslaved or segregated and disenfranchised (blacks).
Well, blacks are no longer disenfranchised, the Asian population is growing, and we now have millions and millions of non-white Latinos. We even have a growing Muslim population. Those groups will not casually “melt” into the general population the way, for example, Norwegians or Poles did. Once there are enough of them and they have the vote, they will demand cultural concessions by the general population. It's human nature that they do this. I can't really even blame them for doing it. Our white ancestors didn't "melt" into indigenous populations of the New World, did they?
Now, there's no question that the Democrats and liberals make it worse, but you can't expect a society without pandering politicians, either. If you have a racially diverse society, you'll have lots of liberals and those liberals will pander to the racial factions. It's what they do. Heck, even the Republicans do it (Bush, McCain....).
This is why the “it isn't race, it's culture” mantra is so maddeningly silly. If you have racial diversity, you'll have cultural diversity. It's like fielding an army that is 50% female, and then explaining the resulting problems by saying, “It isn't gender, it's the fact that they get pregnant and have less upper body strength.”
Well, yeah. Women can get pregnant and they have less upper body strength on average. And a racially diverse society will break up into cultural factions once the various racial groups become big enough to have political clout.