I just got off the phone with Xbox support. They say that codes are still being emailed. They also said they don't know where people got the impression that everyone should have them by December 1st originated, but they mainly said that everyone should definitely receive them by Tuesday at the latest. They are continuing to be sent throughout the weekend, and into the start of the week.
If you do not receive a code by Tuesday, they suggest calling again.
So if you haven't received a code yet... evidently at least... there is hope.
Peace.