Five Million Germans Come to Denmark - A Thought Experiment

How would Denmark react to a wave of mass immigration, numbering several million people, from Germany? The question is, needless to say, purely hypothetical - so much so that one may wonder whether posing it, as a thought experiment, can shed any light on real-life issues and controversies on immigration and integration. I would argue that it can, in some ways precisely because the imaginary case is so far removed from what actually happens. It can thus provide an opportunity for addressing some fundamental issues of immigration and modern nation state without the "distraction" caused by the context in which scholarly and public discussions on immigration - at any rate, in the West - are usually conducted.