It's nice that they're trying to adapt this novel and it's always fun to see Brad Pitt in anything, but the power of the novel was the way it limited your "vision" to just a series of disconnected anecdotes, which was an effect similar to a camera that shows you only one corner of the room, while you know there's Bad Things lurking just out of frame...stringing the stories into a tighter narrative will defeat the purpose.
The one overarching theme from the book seemed to be the South African "solution" that worked, but still haunts the survivors - maybe Pitt will play the sociopathic South African guy who came up with that idea.