It takes a LONG TIME for people to integrate. The New World has this expectation built in, but if anything the United States is probably better at it than other places like Canada and South America where the connections to England, France, Spain, and Portugal are still very strong. For a country without the expectation of immigration as part of it's culture, the process can be expected to take even longer. Like a hundred years or so.
What is more difficult today is that you have more exposure mentally to the new country's culture and the old one due to the internet and communication possibilities compared to hundred years ago.
In the old day you had to accept that your are "stuck" in the new world and tried to make the best out of it. The average immigrant in the old days was most likely so poor arriving in the new country that he couldn't afford to "make a trip back home" that easily.
Today's immigrants stay culturally at home and just come physically to the new country to make some money. If they don't achieve that (and remain unemployed), but on the other hand are that well secured through a functioning social security net (like in France - at least to the point that they don't become homeless or hungry), immigrants get paralysed.
They can't go home (being ashamed to not have made money in the new world) and the can't really integrate and make it in the new world either.
So, they get pretty depressed and frustrated mentally. It seems to me that in the old days all immigrants were finally proud to have made it in the new country and had not only integrated but often over-identified with the new country. I don't think that's so clearly the case anymore for today's immigrants from African countries into Europe.
This, I think, is a very common and wrong view from outside. What you perceive as staying culturally at home is most probably staying somewhere halfway between old home and new home. *Lunatic*, n. One whose delusions are out of fashion.
