It depends on how much those identities differ from the host country's. Russian immigrants to France integrate very easily and the problem (segregation or assimilation) isn't even posed. Migrants can have difficulties to adapt due to lack of enough access opportunities, or locals' negative attitude, but also due to their own lack of understanding, or negative attitude towards local values. Without necessarily assumming ill will from either side , I think the problem must be considered both ways. Free at last! Free at last! Thank God Almighty, we are free at last! (Martin Luther King)
