I'm dredging this back for Zulu and maybe Morocco.
We know that they've touted the large number of civs that you can choose from for this scenario, and we know the three groups. Here's what I'm thinking it looks like -
Europe: France, England, Germany, Portugal, Spain, (Italy), (Belgium)
North Africa: Egypt, Morocco, Algeria
Sub-Saharan Africa: Ethiopia, Zulu, ????,
We'll have duplicates in there somewhere probably, but that's what I expect more generally. More specifically, Belgium could be a full civ or a Netherlands duplicate. The comments about civilizations associated with new late-game mechanics makes them seem possible, but it's really tough to imagine for reasons that have already been widely noted.
Italy could be a full civ, maybe Rome duplicate. Ethiopia's almost certain presence almost demands them, but Rome standing in for Italy here doesn't really feel right, making me think Italy might get in. I'm not a huge proponent of that, but that's my feeling, especially since they fit into the ideology scheme well too. I don't think both Belgium or Italy will get in.
As far as North Africa, Morocco makes sense as a full civ from everything we've learned, and if you add them you have a great stand-in to duplicate Algeria.
In Sub-Saharan Africa, neither Ethiopia or Zulu represents a good double for anyone, but I dunno how much they care about that. This one is wide open, could be a new civ, could be a duplicate, could be nothing. I know what I think makes sense, but I don't have any great clues to go on besides history.