This does not mean that a Drupal core security release will necessarily take place on that date for either the Drupal 6 or Drupal 7 branches, only that you should prepare to look out for one (and be ready to update your Drupal sites in the event that the Drupal security team decides to make a release). There will be no bug fix release on this date; the next window for a Drupal core bug fix release is Wednesday, January 7.