Ubisoft is taking the year off to improve the game mechanics.
http://blog.ubi.com/a-message-from-the-assassins-creed-team/
quote:
This year, we also are stepping back and re-examining the Assassin's Creed franchise. As a result, we've decided that there will not be a new Assassin's Creed game in 2016. Since the release of Assassin's Creed Unity, we've learned a lot based on your feedback. We've also updated our development processes and recommitted to making Assassin's Creed a premier open-world franchise. We're taking this year to evolve the game mechanics and to make sure we're delivering on the promise of Assassin's Creed offering unique and memorable gameplay experiences that make history everyone's playground.
We'll have more to share on all of the above soon. In the meantime, we want to say thank you to our millions of fans around the world for your continued support.
http://blog.ubi.com/a-message-from-the-assassins-creed-team/