You clearly haven't traveled much.
I don't need to.
This is the reason why we have ethnic enclaves in our cities. We encourage non-assimilation and encourage people from other parts of the world to cling to their own and remain linguistically isolated. By emphasizing polylingualism we not only keep foreigners isolated from the political and administrative policies of this country but we keep them isolated from one another too. This is not multiculturalism. This is tribalism.
Amazing how you can live a life of lies. I don't know a child of an immigrant that hasn't learned English. The ESL evening classes in local schools overflow, and are often to get into. Those enclaves as you call them will wind up being tourist attractions, like "Little Italys" and "Chinatowns." We see that happening now in Miami's "Little Havana".
If you believe this nativism you preach, I suggest that you have low self-esteem and controlled by fear.
Stop blaming others for your failures. Instead of being a dick about the subject, why not push your locality for more ESL courses for adults. I guarantee those classes will fill up.