Their children speak English, and their grandchildren mostly speak only English. Meanwhile adult English classes run waiting lists — the demand outruns the seats, not the other way around.

The National Academies of Sciences reviewed the evidence on immigrant integration and found the pattern is not just present but fast, and unchanged from earlier waves: the first generation learns what English it can as an adult, the second generation is proficient, and the third is usually English-monolingual. Measured across generations, English is not losing. The heritage language is.

The adult picture is a capacity problem, not a willingness problem. Federally funded adult English classes are heavily oversubscribed, with waiting lists in many cities running months or longer. People are queueing to take the class the complaint says they refuse to take. Adults working two jobs also learn languages slowly — which is a fact about time, not about character.

It is worth noticing what "assimilate" is doing in the sentence. Every measurable indicator — English acquisition across generations, intermarriage, military service, residential dispersion — moves the same direction it always has. What people usually hear when they say it is an accent, in an adult, in one generation. That is not a failure to assimilate. It is what assimilation sounds like while it happens.