AH Challenge: Massive European Demographic Shift
All this talk about the plummeting European birthrate has got me thinking: what are some of the things that might occur to cause "reverse colonization", that is, an even greater influx of immigrants to Europe hailing from the Middle East and Africa, combined with immigrants from North America, Central America, Southeast and East asia, as well as even Oceania?
What I'm particularly interested in is the immigration of North America and Asia's intelligenica into Great Britain and Northwestern Europe. What would have to happen in the U.S./Canada/Japan (barring natural catastrophes, thermonuclear war, or economic disaster) in order to have millions of citizens of those countries depart for Europe? What would Europe look like after a few decades of this?