The ending is based on the original Bolivian Army ending. You can check it out in TV tropes and idioms. In that ending, it's implied that they did not survive. Although it is possible that they did, and she did leave it up to the fanfic writers to decide what did and didn't happen. Of course if I was a good fanfic writer, I'd just rewrite the whole thing, or use the time matrix as a reset button.