The FBI might get stuff that can incriminate Hillary for some of the charges others have mentioned (risking secret info, etc). That is what would be in any 'recovered' files the FBI may have.
As always, time will tell, but I wouldn't expect them to release the real goodies.
The FBI has everything from Kendall. It was all subpoenaed months ago and I can assure you he complied. Jail is not a fun place for a lawyer. Bubba just loves you.