he problem, I think, is that to qualify for real superpower status, Africa needs a serious edge on the competition early on. The natural resources are rich enough, but the GGS problem remains - poor crop packages, high disease prevalence, limited number of domesticated animals, poor transport infrastructure. If you take a late POD with Europeans or Asians settling in Subsaharan Africa and turning it into a modern power, you can't credibly get to superpower status without doing nasty things to the rest of the world first (an 'On the Beach' scenario with Australia/NZ facing the African Union as the world's sole functioning power blocs after a global nuclear war). Major power is feasible, but beyond that I can't see it. So an early POD that shifts some of the problems would be required. I think a good starting point would be coastal navigation moving Eurasian crops and livestock along the continent. They don't do terribly well in the equatorial coastal regions, but once they reach the more suited parts (the Central Highlands and South Africa), local civilisation can base itself on a more solid foundation than OTL. If we could somehow add American crops, too... maize and squashes do very, very well there.