What happens when you break away from traditional culture, preferably with some examples!

Yes, there are many examples, especially in the area of speech. For example, there was an ancient Indian tribe in the western United States that used the Catawba language, but due to cultural assimilation, the last speaker of the language died a few years ago and the language died out. And the starkest example is that in some areas, children don't speak the dialect but only Mandarin?