After all the Towers of Midnight were mentioned in the question, and then RJ himself used the term Towers of Midnight twice in his answer. Would be a pretty strange mistake for him to confuse it with the Tower of Ravens (not impossible, though, considering e.g. his mistake about Graendal not seen at the Cleansing..). It's certainly possible that the Towers of Midnight eventually also became a prison like the Tower of Ravens. We will see.