A linguist explains how the “three generation pattern” could wipe out Spanish in the US
If one looks only at immigration patterns over the past half-century, it is true that the US has been gaining Spanish-speakers. [...] While new immigrants bring Spanish with them, research shows that their children tend to become bilinguals who overwhelmingly prefer English. As a result, the same immigrants’ grandchildren likely speak English only.
Linguists call this phenomenon “the three-generation pattern.” In essence, it means that non-English languages in the US are lost by or during the third generation.
It matches my experience. What's yours?
Language is like a muscle, if you don't exercise it, you lose it.