The system, or 'family', key would appear to be cryptographically
useless, since *every* chip must know it and be able to remove its
effects from the bitstream.  I daresay that it will be widely known
almost immediately after this system is deployed, and since it's been
pointed out that there is not a separate decrypt key -- the same key
is used for both encryption and decryption -- there goes any benefit
to the use of a system-wide key in SkipJack.