I am a strong believer in requiring all imigrants to learn English, but the Mexicans are hardly the first to retain their native language as long as possible.
There was a lot of German settlement in central Texas in the 1840s, when Texas was an independant Republic. As late as the 1960s, after 120 years, most of the older generation could not speak English.
The Cajuns in South Louisiana spoke "Cajun French" for 200 years, until forced to learn English after WW II.
The point is that no group has willingly given up their native language. They have all been coerced into speaking English and we are gonna have to wake up and coerce Hispanic immigrants to do the same.
So9
The difference is that there's never in U.S. history been a large-population immigrant group, with heavy daily influx from an adjoining non-English-speaking homeland, colonizing a huge contiguous region of the U.S.
That's why reconquista cannot be in any way analogized to Poles in Detroit, Jews in NYC, or even Little Havana in Miami.
I am a strong believer in requiring all imigrants to know English before they get here.