^ Like I say, the Bane-as-Ras'-son is totally speculative on my part. But Nolan and Goyer have departed from traditional Bat-mythos when it suited them. The Waynes were coming from an opera when they were murdered in Begins, as oppose to a Zorro movie in the comics. There was the Ras/ Ducard amalgam and Ras not being Arabic as he was in the comics. Harvey Dent's wife and family were dropped and his transformation into Two-Face also differed from the comics. Then you have The Joker not having white skin, Scarecrow being much younger than generally drawn in the comics, Alfred being a cockney etc.
So I don't think that Bane being South American and not being Ras's son in the comics would be a bar to this plot development.