Integration is a two-way street. I've known many people born in England, France, Germany who feel excluded from education opportunities, workplace opportunities, healthcare and general civil society because of their family origin, cultural background and pure skin colour. Probably also how they speak in the UK. This issue is much less in new world countries (US, Canada, Australia, New Zealand).
Let people into society and they will be part of it. Exclude them and they will form their own societies which you will have far greater issue with.
Edit - some examples - Several in the UK grew up in areas with poor schooling because of where they were born (places cheap enough for immigrants to move to). One who for similar reasons (poor local health service as a child) believes they have avoidable ongoing health issues. Black man im the UK cant flag a cab because they just wont stop for him despite being well dressed in a suit. Turkish-parent German feels pushed into 'workplace training school' (sorry I don't know the term) rather than university because of his background - had to do an extra 2 years of study "just because my parents are from Turkey". French woman of notth african ancestry felt she had to leave the country because she is constantly asked "where are you from" and they won't take "France" as an answer. Common thread is none of these people (all well spoken, well dressed, educated, well mannered) feel they had a chance at being part of mainstream society in their country of birth.
Let people into society and they will be part of it. Exclude them and they will form their own societies which you will have far greater issue with.
Edit - some examples - Several in the UK grew up in areas with poor schooling because of where they were born (places cheap enough for immigrants to move to). One who for similar reasons (poor local health service as a child) believes they have avoidable ongoing health issues. Black man im the UK cant flag a cab because they just wont stop for him despite being well dressed in a suit. Turkish-parent German feels pushed into 'workplace training school' (sorry I don't know the term) rather than university because of his background - had to do an extra 2 years of study "just because my parents are from Turkey". French woman of notth african ancestry felt she had to leave the country because she is constantly asked "where are you from" and they won't take "France" as an answer. Common thread is none of these people (all well spoken, well dressed, educated, well mannered) feel they had a chance at being part of mainstream society in their country of birth.