I take sims leaks with a big bit of 'we'll see'. Even if something is true, the sims development seems pretty changeable anyway, like project rene taking a very different course to what we were told by the TS4 team a while back.
Anyway, African world! While I would love an African world, I don't think it would make sense as a free world. We need things to put in it that fit the theme, so lots of build buy, furniture, decorations, CAS for sims that live there. The world without this isn't really functional as an African world, it would be like sulani without any of the matching content to fill it. If they're going to make an African world I think it needs to be part of an expansion where we're getting things to put in it.
Still, I would love an African world, that would be cool. But not without stuff to put in it.