Left 4 Dead 3 possibly leaked by Valve's employee.

A new screenshot has surfaced to the Internet leaked by ValveTime a Valve fan site.  It was taken from a tutorial by Valve’s Artist Tristan Reidford for Destinations Workshop tools. Of course, this was possibly an accident and there’s a very good chance that Valve employees all have Left 4 Dead 3, Half Life 3, and Portal 3 folders on their computers, regardless of the status of those games. In 2014, the co-creator of Counter-Strike, who no longer works at Valve, stated that Left 4 Dead 3 was in development at that time and “looks great.”
As of now, the image has been replaced by another one potentially revealing there is indeed a new Left 4 Dead game.