I never said that there was that much of a problem with European immigration. However, it even took time for some of those to assimilate, but you don't seem to figure the social incohesion when groups of many different races live amongst each other. I'm not going to act like it doesn't exist, as it has been human nature for people to seek out living areas in which the residents predominately look, think, and act like them. Hence, liberal areas, asian areas, black areas, white areas, etc.
My point is that with such huge numbers, along with social politics and the loss of the enforcement of assimilation, along with huge numbers outside of the dominant cultural stock, this country will most likely break-down in its cohesion. I think that it is highly likely this will be the result, and I don't think that seeing things this way is unrealistic.
Again, I'm trying to look at things realistically.