1. If Clinton is indicted before the election
The FBI merely said that they are reopening their investigation to examine new emails that came to light. They have yet to even determine whether the emails are actually evidence of criminal activity, let alone decide whether or not to prosecute. Therefore, it’s highly unlikely that an indictment would come before November 8. If it did, the indictment itself wouldn’t mean that Clinton could no longer run, as an indictment is only an accusation, not a conviction….
2. If Clinton steps down before the election
Should Clinton relinquish her candidacy before the election, the Democratic National Committee has rules in place for what happens next. Article 2, Section 7 of the DNC Bylaws says that if there is a vacancy on the national ticket, a special meeting of the Committee “shall be held on the call of the Chairperson,” where they would choose a new candidate. Such meetings make decisions based on a majority of those in attendance. Since we are exactly 11 days away from the election, there is one major problem: The ballot deadlines have passed in nearly every state.