A 2014 OECD report "Policy Challenges for the Next 50 Years" envisages an average annual growth rate up to 2060 of 3%.
Paul Mason the Channel 4 News economics editor comments in his new book on Postcapitalism:
“To make the OECD's central growth scenario work, Europe and the USA have to absorb 50 million migrants each between now and 2060.”
That's a million a year on average or 5 "millions" over 5 years. True, the OECD doesn't think that will happen but then neither will growth which, of course, depends on using more and more labour. On the other hand, if the capitalist economy does grow at that rate then millions of migrants will be pulled in, regardless of what the anti-immigration lobby might want. Perhaps the Tory minister Hammond who described Europe being threatened by marauding Africans could go along with this as long as they don't come from Africa.