The thing is that it's not the president's place to pursue prosecution. It's up the FBI to present a case to the attorney general who then decides whether or not to prosecute. Congress can also do investigation and recommend prosecution or not.

The president can, of course, direct or influence the AG which is what many people think might have happened in this case.

Once this administration takes place on Jan 22, if congress or the FBI does investigation and decides to turn it over to the justice department, this justice department might not be quite as lenient on Hillary.

Or who knows. Maybe Comey was right and there's nothing there.