If Eric Holder is held in Contempt of Congress, the issue goes the US Attorney for DC for prosecution.
Unfortunately, his boss is, well, Eric Holder.
In the unlikely event Holder is convicted of contempt of Congress the punishment is up to $1000 fine and up to 12 months in prison.
Considering the late date, it is likely that any citation referred by the full House to the U.S. Attorney would not be disposed of before the election. If the election goes right, it would be handled under a new administration and possibly a new U.S. Attorney.