Witcher 3 is a beautiful accomplishment, and a very well done game - a masterpiece to be certain. But it didn'T redefine society'S relation to gaming, it didn'T redefine people's conception of video-gaming. It was a magnificent refinement of what had come before.
A shattering moment in gaming history, for me, would have to be something that completely redefine our understanding of what video-game are, what they can be. How they're played, and our relation to them.
There is a game that came out in the past two years that has a shot at becoming THAT kind of moment (And it'S not there yet, and may not get there). But it came out this month, not last year, and is not out worldwide yet.