Geni, if you speak about nationalism, you have to look at the sources of nationalism. There are some nationalist tendencies in Catalonia. Why? Cause the Spanish tried to erase the Catalan language and the Catalans were forced to defend their identity. There are nationalist tendencies in Spain. The sucessful fight for autonomy of the Catalans takes away regions which were formerly seen as integral parts of the Spanish language area. The Spanish feel a threat for their identity. There are nationalist tendencies in the USA. Why? Cause the number of Spanish speakers rises and rises in the South (and not only in the South).
People become nationalist when they realize, that their language/culture* is threatened or on the downward path. Wanting to abolish all the languages of the world except one will lead to a massive rise in nationalist tendencies.
* Please be aware, that language is not merely a medium to transport information, it is information in itself. Language and culture are intertwined and cannot be separated. Shakespeare is popular in English speaking areas, Goethe in German speaking, Zola in French speaking, Groth in Low Saxon speaking and Si Mohand in Kabyl speaking areas. Their works can be translated and are translated, but translations rarely reach the depth of the original. They are out of their meaningful context. In a monolingual world there is no way for Germans to keep their German culture or Kabyls to keep their Kabyl culture. Goethe and Si Mohand are meaningless without the German and Kabyl language. There are 6000 languages in the world. Each of them has their own songs, traditions, tales etc. You would kill and make meaningless 99 % of that cultural production only to make it easier to write an encyclopedia? If you are worried about reduplication of effort, please first start lobbying for a ban on Britannica and Encarta.
Marcus Buck