No one, which I believe is his point?

Nowdays they might flee from muslim immigrants, just suppose.

Yes, but they mostly live in the suburbs of cities like Paris, while the inner city remains affluent and white. Do Europeans just do a more effective job of keeping poor people and ethnic minorities from moving into the inner cities in the first place?

A lot of continental inner-cities (Paris, most Italian towns) were already too expensive way before "immigration waves" were even possible. In that sense, newcomers never got a chance. Any town that has existed since Roman times has had two thousand years in which to solidify the link between location and social status, to a point that will likely survive anything bar catastrophic events.

The suburbs didn't exist when people started immigrating to cities like Detroit.

It's not a coincidence that curry is so popular in Britain.