What will really change bitcoin's fate is some small nations using it as a currency

I am unpersuaded by your argument that that any nation would do that (because nations that cannot make a credible commitment to good monetary policy can just peg their currency to the dollar). Much more likely IMHO that some wealthy actor like Tehran or the Chavez administration will increase the appeal of accepting and holding bitcoins by offering to swap bitcoins for, e.g., heating oil as a way of sticking it to the US government.