Today, the official website for the Metro 2035 novel by Dmitry Glukhovsky revealed that the next game in the Metro series will launch sometime in 2017.

Details at the moment are scarce, but the following teasing blurb accompanies the game which is currently titled as "The next Metro video game."

It all adds up to something. Where the books end their story, the game will pick it up. An era of great discoveries lies ahead…
In a timeline on the website, Glukhovsky lists “the next Metro video game” for a release sometime in 2017.
Update 11/9/16 at 11:55 a.m.: The official Metro Facebook page has provided the following update:
You may have noticed some sites have reported that a new Metro game would be released in 2017. Deep Silver has released the following statement… As the exclusive rights holder to videogames set in the Metro 2033 universe, Deep Silver has ambitious plans for the hugely successful Metro series. But just to manage our fans’ expectations – releasing the next Metro game in 2017 is not one of them. When we have more news to share, we will. Thank you for your patience.