if Hillary shows herself to be terminally weak against Trump (the likely nominee of the GOP), then Obama will OK the justice department to indict Hillary. She will resign as nominee and Biden will step in.
As much as I hate Obama, I don't think the federal justice system looks to him for 'thumbs up, thumps down' to proceed. If he had his way I think she would have been indicted already. If the FBI puts forward information based on their investigation that there is 'probable cause' federal crimes have occurred, they must forward the information to a federal grand jury which means 12 jurors (regular peeps') need to all agree, politics aside (uhhu). My prediction: It will make it to a grand jury but there is no way in hell in this day and age that 12 people will agree. Her proclamation: "I didn't do anything wrong because a Grand Jury said so.
Biden won't step in because the Dem machine won't let him. He's every bit as toxic as Obama would be should he be allowed to run for a third term.