My feeling is we may get more than originally planned but the update may be split into two: december and january. Don't forget if there is a holiday event there is typically a maintenance to begin it and another one to end it.
One thing that I was wondering about was:
There are two updates planned: Mid-december update, and Early 2011.
We also know, there is 100% a patch in March 2011 (PS3 release)
The question is- Is Early 2011 "Jan/Feb 2011", or is it PS3 release?
Evidence towards Jan/Feb: Early 2011 would simply be called "During the PS3 release" / "March 2011"
Evidence towards March: Square Enix works by quarters.