According to the Dutch Statistics Bureau by 2050 there will be 16.8 million people in the Netherlands, which is 400,000 more than today. 1.6 million will be immigrants. The growth will be mainly due to immigrants and their part in the population will grow to about a third.
The decline in the ethnic population as well as their part in the population will continue unabated. In 2050 there are expected to be 12 million, which is 1.2 million less than today.
The sharpest growth is by the non-Western immigrants. Those are defined as people who have at least one parent from a non-Western country (not including Indonesia and Japan). Their numbers will grow from 1.7 million to 2.7 million. Together with the Western immigrants the total immigrant population will grow from 1.4 million today to 2.1 million - about 29% of the population.
The growth in the non-Western immigrant group is accounted almost wholly by the 2nd generation, which are born in the Netherlands. This includes not only Turks and Moroccans but also the more recent and mostly young asylum seekers from especially Iran, Iraq and Afghanistan.
Source: Elservier (Dutch)
See also: Netherlands: 50% immigrants among youth in cities (saying that by 2030 the non-Western immigrant population in the medium and bigger cities will be 30%).