Not at all! These are very small countries with Similar smaller contribution ti the world GDP. What they are doing, is for their own benefits and the world doesn't follow their footsteps. So having bitcoin as a world currency, is not possible.
For such small and economically weak countries, there is not much difference in using dollar or bitcoin, since their own local currencies are subject to significant inflation. Therefore, they choose bitcoin, since from a standpoint of profit this is a better solution. It has nothing to do with world currency and I think it's too early to talk about it.
But yes, if suddenly US adopts bitcoin as a legal tender and remove dollars from their economy (won't happen), then bitcoin has a chance of becoming world currency. Otherwise it's impossible!
I consider what you said as the most likely thing that could happen in the future, and I also tend to believe that bitcoin will never become a world currency. Not because bitcoin is bad for that or anything like that, but because I assume that
BTC will serve a different role in the future than being used as the world's currency.