I don't think Europe would be necessarily primitive; they'll have citilization, but its easy to envision that they could be and remain backwards. I'm not sure about Africa becoming dominant, but the Muslim states I can envision maintaining their technological, cultural and scientific edge over Europe and become the first too industrialize without too many PODs. Its out there, but the notion of Muslim countries placing Europe under colonial rule isn't completely implausible.
As for powerful Sub-Saharan African civilizations. The best I can envision is a Mali Empire based on Timbuktu that gains its wealth from trade with the prosperous Islamic world, and with Europe remaining feudal this trade route would always remain an important one. Eithiopia could also become powerful, but I don't envision that many others.