What is the duration of the game?

I know the game isn't out yet, but I'm interested to know what the game time will be like.

My worst nightmare would be if the demo was 1/4 or even 1/5 of the game (meaning the game would be around 15-20 hours long). I hope and expect the game to be around 30-40 hours long, just like Greedfall.

I've been looking forward to this game since 2 years ago (not 100% sure if it was announced 2 years ago, so correct me if I'm wrong) and have been following its development ever since. It would be depressing to get only 20 hours of pleasure in 2 years of waiting.