There have been Turkish "guest workers" in Germany for many generations now (that is, the grandkids of the guest workers are still guest workers, not Germans). They are German in all but descent, but only 15 years ago did they begin to allow a trickle of these folks become German citizens. If Germans are upset about multiculturalism and want folks to integrate, I can't think of a better way to fail at this than to not really allow them to integrate and then get mad at them when they don't.