For decades Europe ignored the legitimate fears being raised about unfettered immigration. Now they are seeing a rise in nationalistic governments. Now I don't view nationalism as a positive or a negative, it simply is. It is an extension of the tribal mentality that every human being has whether we want to admit it or not. People identify with groups, be it a small tribe of hundred or a nation of a hundred million. But nationalism can get out of hand, we saw this at the beginning of the last century.
What we are seeing now is force that could spell the death of the European Union. Governments are now starting to actively act within their own national best interest, despite the fact that it would violate, if not legally, then conceptually of the European Union. Yet there are lessons for the United States, which have always done a better job with assimilation, to take head. If the US continues to not enforce the laws* that it has towards illegal immigration it will face the same sort of unrest.
*As I have said before I am all for a revision of the laws on our books. It is absurdly difficult for people, many of whom would be very productive, to come here legally. People are human capital, and as I will state in a later post, there will be a battle for human capital in the future.