That population also has to be relatively peaceful.
I don’t see the Arabs in Europe peacefully accepting forced deportation. As we have seen in France the young Arab population is not above a little violence and vandalism.
If Europe tries some ethnic cleansing by removing the Arab/Muslim population I can only see it coming to blood in the streets and seeing that the Muslims are more prone to violence than your typical European I think there will be a goodly amount of European blood on the street.
Unless European countries in some grouping create a new curtain, the Muslim population will simply shift around, more like what happened with anti-Jew, anti-Gypsy, anti-Greek and anti-Ruthian etc kingdoms for several centuries before WWII.
So until a solid curtain of countries some how simultaneously close their borders, and the Eurozone passport treaties are nullified, and the trading partners of thee countries don’t boycott them, nothing will happen in Europe.
The best possibility would be for widespread reductions in social safety net expenditures to balance the budgets, forcing each European to personally look at the government budgets.
Quite frankly, the average European resident, be it native or immigrant, is more endangered by a collapsing social safety net in the short term and medium term time frames, than by the long term problem of replacement population immigration policy.
Portugal and southern Spain will be leading examples, both are completely bankrupt, there isn’t enough money to feed their own kids, let alone another immigrant mouth.