I think that would qualify as ethnic cleansing to some extent, and don't think it would be moral. At the very least countries should be very upfront about their intentions if that is their plan. Imagine if you had to emigrate to China and was forcefully interned in a re-education camp...

Looking at the US, it does just fine integrating different cultures from all over the world. All the problem ethnicities in Europe are gainfully employed model citizens in the US. One should maybe ask what is going wrong in Europe before resorting to extreme measures.