"I doubt, though, many of them arrive in America thinking they will leave behind their religion, language, and values."

If they don't think that, then they have a certain amount of unreality in their heads. Can anyone here seriously say they'd expect to go elsewhere and NOT adopt at least some social customs? And then the following generation adopt more? It is ALWAYS a struggle for third-generation Canadians to hang onto their mother tongues. But we still come back to the same thing: the more people isolate themselves or are isolated or some combination of both (as a group or as individuals), the less they are involved in government and the less input they have. It is not in the interests of Washington or Ottawa to change the balance. So guess what? The balance doesn't change.