Dollar is a popular not just popular but a powerful currency. It is very known world wide. Some country also depends on US dollar, making it powerful, so i don't think it will happen soon. Maybe someday but not so soon.
yes that is right that dollar is too much popular as well as powerful but it is only because of its users, if people will stop using dollar i do not think that it will even survive for some time. in fact the young generation are now changing their interest, most of them are now using online facilities for shopping and for so many other activities. so i am sure that if this trend will continue for a long time then dollar will really become devalue and people will mostly give preference to online currencies.