The announcement was made by a member of the EA Madden team, via EA Answers HQ, and notes that Madden NFL 17 and Madden NFL Blitz will be retired at the end of the year. Interestingly, the Discontinuation of EA Online Services The page says Madden NFL 17 will be shutting down on December 3, so if you have any accomplishments to mop up before the shutdown, we recommend that you look to complete it before December 3 just to be on the safe side. The shutdown will affect the Xbox One and Xbox 360 versions of the game, but offline modes will still be available after the dates listed above.
Madden NFL 17 has an estimated completion time of 15-20 hours, with just 3% of the 64,000 TA players completing it. It looks like it shouldn’t be too difficult to complete, with only the achievements of the Champion and Tom Brady Legacy Award providing a bit of a challenge. The Champion requires you to complete a Draft of the Undefeated Draft Champions, and the Tom Brady Legacy Award tasks you with creating a Player, Coach, or Owner and getting a legacy score of over 25,000 with them. There are, however, five achievements flagged as either unobtainable or partially discontinued, so a full completion could be irrelevant anyway.
We recommend that you aim to have Madden NFL 17 complete by December 3 to be sure, just in case the December 7 announcement is wrong.