What happens when they start to see their ethnicity or culture as political and fight to impose it, including using violence? Because at some point it will happen - democracy incentivizes clientelism and tribalism.
The USA, which is often touted as a "successful" melting pot model, is rife with similar problems.
>democracy incentivizes clientelism and tribalism
Cite your peer reviewed sources.
Civil strife? If it comes to violence, I (a white person) certainly won't be on the side of the white nationalists. Same for most of my peers.
Many of us love living in multicultural societies and will fight to protect our neighbors and our way of life.