This is an interesting article in the New York Sun, concerning the centrifugal forces pulling bilingual Belgium apart. Roughly sixty percent of the Belgian populace - the Flemish - speak Dutch. About a third of the Belgian populace - the Walloons - speak French. Surprise, surprise, they don't like each other much.
Belgium is in fact an artificial creation of nineteenth century geopolitics. As the article points out, Belgium has had no government since early June. The people of Belgium might well vote to separate with the southern Walloon section joining France and the northern Flemish section joining the Netherlands. This tends to be the fate of multilingual nations.
The United States should do some vicarious learning here; we should watch what is happening to Belgium and resolve not to become a bilingual nation. We should only print government documents in English, should require English for a driver's license or a ballot or a green card, and should make teaching English as a Second Language a major component of public education.