That was a test screenshot. It was never stated that Verdistis will be in the game. At the time they were experimenting with the new game engine and learning how to use it. It was to give us an idea of what to expect.
Though like that famous Link and Ganondorf battle CGI film Nintendo released before the Wind Waker, we all assumed we'd see Verdistis when it was only a graphical demonstration of the new game play engine.
It is far more evident that a Divinity 3 will be released provided sales do well and I don't see why they wouldn't do well.
