No doubt about that. Bitcoin is an option to those countries who wants it. Besides, government don't want something that is out of control, and bitcoin is uncontrollable, so it is way off to become a main currency of a certain country.
Anyway, dollar is strong, it was tested by time and it is still there, still on top, so I think, it's hard for bitcoin to replace it, unless the people/government wants it and if Bitcoin will be good for them.