This is pure nonsense. You might as well that the person who is the biggest creditor is the same as the biggest debtor via some horseshoe theory of finance. The Euro can't be a reserve currency because the Eurozone cannot support large capital inflows, which is because Germany is dependent on having an export based economy. Seriously, you are confusing plus with minus, addition with subtraction. To be an issuer of reserves requires that you allow foreigners to run surpluses against you. Thus no currency zone that requires running surpluses is going to be a reserve currency as long as plus is not the same as minus.