> And of course this has turned Brussels into an extremely non-mixed city. The ghettos are ethnicity based now.

I have a feeling that it is not entirely the immigrants' fault for this state of affairs that they self-segregate or exclude natives from their social circles.

I speculate that it's got to do to some degree with racist and nativist Belgian politicians or European politicians in general who benefit enormously from a failure of the multi-culturalism experience and integration/assimilation by immigrants to warrant a xenophobic and hateful reaction like deportations, internment or barring of entry.