>it's also breeding resentment because of assumptions by "outlanders" that learning local norms and language is optional to the point Dutch speakers can feel strangers in their own land.

I was wondering about this too; did not see any charts/data/observations of it in the article. I thought outlanders assimilate to become inlanders, but it looks like that takes a long time and presents as social tensions: "What do you want the country to look like, in a reasonably forward-looking way?"