From the way he's describing it, this would be exactly the reason why TW2 would be at a lower price than standard on GOG.com - because a standard price is inclusive of physical content.
Then, there's places like Steam, who have normal prices for digital editions. But i just don't see the reasoning in "TW2 on GOG", it's neither old, nor would it cost $9,99, it just doesn't fit.
I just can't see CDP using GOG as a digital distribution site for their games. It's like making it another Steam-like platform [minus the DRM of course]. It just doesn't make sense.
 and TW2 is coming to Steam, teehee, extra feature: teh evil DRM? ;P