This video, spotted by Beefjack , seems to show footage from a Thief 4 CGI demo reel. The demo was uploaded to YouTube by "garrettisback" and the video tagged "thief4demoreel." Eric Wong is mentioned at the start of the video, which seems to be this chap . His experience list mentions a stint as a lighting artist with Eidos Montreal working on Deus Ex: Human Revolution and Thief 4 back in 2010/2011. Some leaked storyboard images tagged 2010 showed a few scenes similar to those in the video above. They're embedded below.
So, all in all, it looks like this is Thief 4. Or an elaborate hoax. Either way, it seems to capture the Thief vibe quite nicely, with a few extra flourishes, like the unfolding/folding Hawkeye bow, and Garret's new "look I have a lockpick!" pose.