Leonardo said:

To address your first post in as few sentences as possible, I can't say I totally agree with it.

Good!

I think "assimilation" (it's been a while since I took anthropology, the terms might have changed, and I didn't pass it anyway) should happen naturally, just letting people be people like they have been for centuries.

This also kind of means they end up forming groups that have rival goals.

I agree with Eyeshotfirst, where he says the U.S. seems to have an ambiguous identity, almost a non-identity ( I hope I'm not mis-interpreting your thought).

The "melting pot" thing doesn't seem to have happened at all... Well, at least for the people who aren't fair skinned.

Well I'm sure it isn't everywhere, but there does seem to be a number of people from different ethnicities who act and behave in an American fashion as well as those who do not.