The idea that English (in this case Spanish and Mandarin as well) will kill all other languages is debious and forget a very important fact: through most of history and in a lot of places bilingualism is the norm. Current examples are some African countries where languages local are spoken and French is used as vehicular language; Standard Chinese while people speak another Sinitic language. What is likely to happen is more people being proficient in a second or even third languages (like it is in Hong Kong).