If you read the demographic projections for the U.S., by 2050 as much as 25% of the American population will be Mexican or other Latinos. It means that there will be two major, different and competing with each other cultural and religious streams: Anglo-Protestant and Spanish-Catholic. The U.S. will never again be the same again. It will have enormous impact not only on the domestic politics but also on the global position of the U.S. and on transatlantic relations. In the meantime in Europe there will be by 2050 as much as 20% Muslims in the whole continent.
See:
The European Courier | European Muslims
There is no doubt it will have additional negative impact on the US-EU relations. Those two groups will actually be able to directly influence foreign policies of the US and EU. There are some proposals, for example in Germany, to pay 25.000 euros for having a baby in order to help white, indigenous Europeans to increase their fertility rate. However such actions will also help increase the fertility rate of the Muslims living in such countries. It seems that the emergence and take over by those two minorities is inevitable. By 2050, Spanish will be as important language in the U.S. as English; the same thing will be with Arabic in Europe. Both the U.S. and EU are experiencing big problems with assimilating Mexicans and Muslims. Those minorities are very reluctant to external influences and live in closed enclaves rejecting culture and religion of other people. In the U.S. it may result in the return to isolationism policies and reorientation of U.S. focus on Latin America issues and possibly furthering economical integration with that region. In Europe it may result with absolute rejection of the U.S. policy in the Middle East and canceling support for Israel. Even now it is happening to some extent. For example the magazine European Voice announced last year Tariq Ramadan the Citizen of the Year. Ramadan is regarded by the U.S. as a financial supporter of Hamas and his visa was revoked by the Department of State in 2004, when he intended to become a professor at the University of Notre Dame. See:
Tariq Ramadan - Wikipedia, the free encyclopedia