The current population movement certainly makes a person wonder what long term and short term affects will be created. On the immediate time frame simply providing suitable housing is a logistical problem as is employment. Where do a million new jobs come from?
Population movements have changed the culture of Europe and the US throughout history. People were displaced by more aggressive cultures and moved elsewhere, and new populations took over. How that will workout now with few if any unpopulated places is sure to create friction.