There is a huge difference between Pennsylvania Germans speaking their native language in early America, and wiping out our native English language now through forced illegal immigration.
The standard idea for the immigrant population (note: legal immigrants) was to learn the native English language. Many households did not encourage their children to speak their native tongue OUTSIDE of the home. They respected this country enough to learn it's language or to at least make it clear to their children that it was a necessity.
According to your thinking, I hope you already know the language. I don't, and don't feel I should. I think they should learn OUR language. What a concept!
According to your thinking, I hope you already know the language. I don't speak Spanish, but English is also not my native language.
In any event, language is a pretty secondary issue. Maybe, someday, this country will be majority Spanish speaking. More likely, English will remain the language for those who want to be succesful in this country. You may be able to get by in Spanish, but you'll never be able to rise above relatively menial, service industry and physical labor work.
People who don't learn to speak proper english are relegating themselves to second-class citizen status. That may be why the parents of hispanic kids are not big fans of bilingual education.