She won’t quit now as it would give the nomination to Sanders. Afterword, maybe. In both, not giving it to Sanders would cause civil war in the party.
First, I don’t think it’s likely she will be indicted, but I do think it’s likely the FBI will recommend it. If they do before the convention the superdelegates will abandon her. Afterwards nothing will get her to quit. It’s the White House or the Big House for Hillary.