There is something very strange and inconsistent regarding the verification upgrade deadline and course deadline. On the home page of "course info" on the right hand side the Verification Upgrade Deadline seems to be given as Dec 15, 2017 while the Course End is Dec 30 2017. While this is certainly not the two weeks that is said to be the general deadline for Edx courses I can understand if some courses have different deadlines. However, on the same page the deadline for the course is given to be 31st Dec 2016 (which would also render the information above regarding verification deadline false.) I would love to know when the actual deadlines are since it seems like some course info may be outdated or contradictory. Any help is appreciated!
It seems that the official course deadline has indeed been changed to December 31st 2017. I was confused too, because there didn't seem to be any kind of announcement detailing an extension.
Regardless, two edX officials have responded to my query in reference to this inconsistency. They both said all work can be completed and submitted before December 31st 2017, and a verified certificate can be attained.
I also find it unnerving. The Submit section in the CS50x Gradebook still displays January 1st 2017 as the deadline, so I feel as though they should edit that to make everything totally clear.
Here is the revised schedule, which also clearly indicates that the deadline is now December 31st 2017.