[theli0nheart]

>> "They moved into a community and it’s their job to integrate with the community."

> Is that a broadly-accepted opinion? Does it apply consistently to all cultures -- e.g. does it apply when nonwhites move into a white area?

If you move to a place and don't respect the local traditions or culture, you're making life harder both on yourself and to the existing community. I see no reason why it wouldn't apply every direction.

> And, does it reflect reality? Do new populations really preserve the prexisting culture in practice?

It largely depends on the societal and cultural homogeneity of the newcomers. If newcomers are largely from the same place or share the same culture, then I'd expect it would be more likely that they'd shift things in their direction.