You can’t rule out any possibility In bitcoin, we already see some countries like El Salvador making bitcoin officially a legal tender.
El Salvador government had to stop their Bitcoin legal tender enforcement with pressure from IMF and they had a deal with IMF with one of conditions is stop the Bitcoin legal tender in their nation.
Bitcoin can become a legal tender officially worldwide but that doesn’t mean every country will have to do away with their local currency, No.
What does No here mean?
Bitcoin will almost impossible become legal tender in many nations. What happened with that policy in El Salvador shows that if IMF already did that with El Salvador, that foundation will try to do the same with many other nations which tend to make Bitcoin legal tender.
Many governments won't feel ready to do that and this reason is a bigger barrier for Bitcoin legal tender globally than IMF.