Herja has asked whether or not white Americans are concerned about being or being about to become a minority. The answer is: as far as I can see, they aren't.
The thing is, white Americans are not a minority, nor are about to become one anytime soon. They are about 75% of population, and are projected to drop slightly by 2042. The projection says that by 2042 the non-Hispanic whites will drop under 50% of the total population, but "non-Hispanic whites" are a rather artificial category.
To put it really bluntly, whites are usually concerned about blacks (more specifically about not being a minority anywhere where blacks are a majority) and the black population is not rising in any significant numbers. The Asian population is rising really fast, but I've never met anyone who'd be concerned about that. Lots of people are concerned about Hispanic immigration in the sense of it being a lot of poorly educated people who don't speak English; very few people regard English-speaking US-educated Hispanics as any kind of a threat.