I'm just guessing here, but I'm not sure that most African countries have a strong sense of "nationality." The history of many African countries is bound up in the colonial conditions that existed for so long.
Obviously, Africa has been exploited by the rest of the world. This has deeply affected its ability to form its own individiual national identities. These identities are necessary for the formation of a national purpose and will.
Yes, African countries can prosper, someday. It may take either a great deal of time, or some series of events that organizes its people into cohesive national groups.