The dollar could not be world reserve currency between tomorrow and whenever, so maybe one day.
As found on wikipedia, 'By the end of the 20th century, the United States dollar was considered the world's most dominant reserve currency, and the world's need for dollars has allowed the United States government as well as Americans to borrow at lower costs, granting them an advantage in excess of $100 billion per year.'
However, the U.S. dollar's status as a reserve currency, by increasing in value, hurts U.S. exporters!