For a dominant Africa, or even an Africa that isn't everybody's punching bag you need three things. !) Better crops, the Columbian exchange brought in a fine set of crops, perhaps some improved trade between Ethiopia and the rest of Africa could establish some other useful crops elsewhere. 2) A less brutal disease climate. The Swahili Coast (or the area we now call the Swahili Coast) was growing rapidly in the period before the
535 event. But the sudden climate change made bubonic plague endemic in the area if you got more than ten miles from the coast. The
Tsetse Fly both brings disease and restricts food supply. 3) Africa had, and still tends to have poor transport. Seagoing cultures they had but little useful wood for shipbuilding and few good ports and inland river traffic was often problematic.
To build a strong Africa you need to deal with all three problems.