Past migrations are a fair point. Of course present-day Poles, for example, haven't been in Poland since the beginning of time. Nonetheless, you now have nations that have been around for hundreds, or thousands of years in their homeland, and share an identity, culture and history (as well as from genetics, regardless of what you say - you can tell a Pole from an Indian, an Indian from an Igbo, and an Igbo from an Amerindian). If Poles were to become a minority within Poland, we would essentially lose this culture and nation of people, which would be a loss for humanity on a similar level as losing the native-American nations was.

I originally mentioned nation-states in response to the suggestion that Brits would be shocked when walking through California, due to the comparatively high amount of minorities. I countered it by stating it is a false equivalence, since America is a totally different type of state. It's a melting pot, and a nation of immigrants. It is an almost unique case, which only certain other ex colonial territories can be compared to.

Yet despite this, it was a false point anyway. Because this is a scene that can be found in many places throughout Western Europe. In the space of little more than a generation we've already seen the native population become minorities, or near-minorities, in their capitals and their biggest cities. This has happened rapidly, and the rate at which it is occurring is only increasing. It is absolutely not sensationalist to state that the demographics of Europe are changing hugely now and are on course to change unrecognisably within just two, or three generations. In fact, with current trends, it would be ignorant or straight-up deceptive to suggest otherwise.