Witch Delay is Why?
Those beautiful, beautiful people at CD Projekt have given the skinny on precisely (precisely!) why they're making us wait so darn tootin' long for Wild Hunt. Sorry folks, they hate us. Just kidding! They love us too much to give us a shoddy, incomplete pile of broken mess. The story you see, is already complete. The main story at least. In fact, it's already fully playable. So whyfore no release? Like I said, they love us too much.
How does that work you ask?
Well, you see. Yes, the campaign is complete and playable, but the engine...I hazard to say it's broken, 'cause this is CDP and...I haven't played it yet. But the point is that CDP themselves are dissatisfied with how it works. Ergo, the delay is for them to do some final bug testing, fixing and (cue orchestral music) further optimisation. They gave details of this in a financial report. It's all in Polish, but that's what we have the mighty babelfish for.
Told you they love us.