There are some decent African teams, but the really good ones have been flukes, like Ivory Coast. Sometimes you just get a golden period in a country out of nowhere. I do think that Africa will start producing better teams though, having the world cup in SA will have sparked more interest in football.
Popularity of Football has always been high in the whole of Africa, 2010 WC didnt change that much towards that imo.
The corruption fucks up any kind of continuity or building a good infrastructure for sports in these countries. Member in these countries the local FA stooges are just in it for themselves, without any real critical feedback from population. They will not invest in their league, continuity, vision, long term strategy or youth academies if they can slosh that money towards themselves.
They have been saying this for decades, Cameroon at 1990's (when they beat Maradona's argentina in opening game) Nigeria mid 90's, Ivory coast with Drogba in the 00's.
I don't think it will happen in the near future, South-American and European top teams are way to professional, consistent and organised for any african country to make a serious swing for a final spot. There have been lots of "surprise semi finalists" in WC history, but at that stage you inadvertently meet the real contenders which are "in form" from the traditional strong countries.