I'm 99% sure that Africa is not going to reach 4.3 billion inhabitants. Climate change, food insecurity, economic growth and global instability will ensure that it doesn't turn out that way.
To illustrate the point: The last 40 years have been the worst we will see in terms of stability, economic growth etc .... yet Population growth in Africa thrived and the % of people living in poverty reduced dramatically and the current population is healthier, wealthier, and more educated than ever before (https://ourworldindata.org/grapher/above-or-below-extreme-po... ).