In 2050, how many people in Europe will be of foreign origin?

According to a 2017 report, "the Muslim share of Germany’s population could grow from 6.1% in 2016 to 19.7% in 2050 if high migration continues" and similar statistics are being shown across the board with a variety of European countries, including the UK and Belgium, seeing just shy of 20% of their population being Muslim by 2050. However, the same report suggests that if migration is slowed, that could less than double in the whopping 30-odd years ahead of us, which seem seems high but hasn't got anything on the figures from the 1960s to now, for instance; some countries have seen migration increase ten times over. While to many natives that may sound like a daunting prospect, the same report shows that there are an enormous level of middle-class, high-skill workers migrating to Europe, which can only be beneficial for the economy long-term. Providing that the governments of countries expecting the highest increase in migration prepare for the most overwrought scenario, the increase has exceptional benefits. If not, it could be detrimental.