Again cultural wars where everyone gets furious and nothing changes.

USA have had even worse hoards of immigrants (irish is one of the worst, yet we had Presidents with irish descendance)

You can voluntarly borrow someone's culture elements, but not to force it. French would never become Algerians and vice versa. They might kill each other, but not assimilate because usually illegal migrants live separate with the host culture in poor ghettos (at least in EU).