While Congress retains its “inherent contempt” authority and may exercise it at any time, this inherent contempt process was last used by the Senate in 1934, in a Senate investigation of airlines and the U.S. Postmaster. After a one-week trial on the Senate floor (presided over by the Vice-President of the United States, acting as Senate President), William P. MacCracken, a lawyer and former Assistant Secretary of Commerce for Aeronautics who had allowed clients to rip up subpoenaed documents, was found guilty and sentenced to 10 days imprisonment.
MacCracken filed a petition of habeas corpus in federal courts to overturn his arrest, but after litigation, the U.S. Supreme Court ruled that Congress had acted constitutionally, and denied the petition in the case Jurney v. MacCracken.
OK, you got that quote from Wiki:
http://en.wikipedia.org/wiki/Contempt_of_Congress
That is the last time any sort of punishment has been given. Farther down that same article on Wiki, it gives a list of what has happened in contempt cases since 1975. Bottom line: most have complied, and only one (Rita Lavelle, a Republican) has suffered any punishment.
Conclusion: Nothing will be done to Holder.