There is widespread grassroots concern about the future of English as the language of America. I have never been particularly worried and this scene from Iran is why:
Those are brandished by the officers of an avowedly anti-British, anti-American regime; and yes they are printed in English. These are streets signs in the same country.
Note that not only is English not a native or official language of Iran, but the alphabet is not even Latin. Yet, the street names are co-listed in English.
English is not the language of the US or even Great Britain. English is the language of the world. Barring worldwide economic disaster, by the year 2075 English will be spoken on the street in every city, in every country in the world. Economically speaking there are large network externalities to using a common language. These externalities suggest that in equilibrium there will be only one language. The road signs suggest that that language will be English.