1. At one time in human history, not long ago, it was mandatory to have some facility in at least a 2nd language to claim you had a higher education. Partial mastery of a 2nd language would help native English speakers "get" what it's like for the non-native people and might help them adjust there speaking style. IMHO we have allowed "higher" education in English speaking countries to devolve in this regard.
2. We might be entering an era where English begins to morph into new dialects as did Latin when it was the "Lingua Franca" of the time. The 2nd language population will overwhelm the native English speakers and so control the language.
( "Lingua Franca" is probably one of those terms that one should not use internationally, unless you are in Italy, Spain, France, Portugal or Romania) :)