bitcoin is a future digital currency, i strongly believes that before BTC celebrate 50 years in existence at least one or two African countries is going to legalis it. because block chain network is expanding every day by day. and most of the countries in Africa have the knowledge BTC how it works.
Do you mean that some African countries will legalize Bitcoin, or do you mean to say that an African country would make Bitcoin a legal tender? What Frankolala said is the truth: Bitcoin is already legal in some African countries, even in Nigeria, where their government once banned crypto interaction with their banks, but later such a ban was lifted, and people are freely using Bitcoin in the country and other African countries too.
If you are assuming that Bitcoin might become a legal tender in Africa in the future, probably before the celebration of Bitcoin's 50 years of existence, then you may be right, but I don't know if that can be possible.