People have too diverse views on poliitics and other human factors, for them to adopt a single currency world wide.
This person does not understand that politics doesn't matter when selecting tools, if one tool is far and away superior than its competitors.
If one is preparing for war, one does not pick up the sling or the spear when the machine gun is loaded and ready.
Bitcoin has already made all other forms of money obsolete. Most of the world simply has not yet figured it out. Rest assured, they will. Sooner rather than later.