Immersion was what helped generations of non-English European children to learn English ASAP when they arrived in this country, and I don't see any reason why it wouldn't do the same for non-English speaking children from other parts of the world. Well, no reason but the teacher's union.
Incidentally, I think one of the reasons that some people on some threads get so riled up about Hispanic immigrants is precisely because of bilingual programs. They are very divisive and give the impression that Hispanics don't really want to learn English or be part of American society. This is not the truth, of course, and many Hispanics have even sued to get their kids out of "bilingual" classes.
"Bilingual education" has been a disaster from just about every perspective.
And the root cause of the high rate of dropouts.