Seriously. Just look at some of GDT's past comments regarding creature design:
(Regarding the creatures in general, with a specific mention of the Wargs)
"I also wanted some of the monsters in The Hobbit to be majestic. I wanted the Wargs to have a certain beauty so that you don't have a massively clear definition: what is beautiful is good and what is ugly is not. Some of the monsters are absolutely gorgeous. The way I phrased it to Weta, I said we would keep the DNA in the same gene pool as the Rings trilogy, but that we would generate a different type of character. For example, in the trilogy most of the creatures are brutish or inarticulate. In The Hobbit, the creatures speak: Smaug has beautiful lines of dialogue; the Great Goblin has beautiful lines of dialogue; many creatures do. So we had to design them with a different approach because you are not just designing things that are scary."
(Regarding the Mirkwood Spiders)
"They are visually quite striking and in a different way to Shelob," he explains. "They are more creatures of the shadow, more creatures of the deep forest… Our spiders have to feel massive but be very nimble."
(Regarding Smaug)
"I wish The Hobbit had been filmed, I wish it had gone, because then I would tell you I did something – I'm not sure that the design will stay that way – but I came up with a thing for Smaug that has never been done, ever. I know every dragon ever made – that has never been done. I'm not sure the Smaug that will stay is that one, but when everything is said and done, you know, when the third volume comes out and we meet again and the movie's out, I'll tell you they did it or not and I'll tell you what the trick was. It's a very simple thing, but it's never been done before. So, you know, I think that is not hard, when you are immersed in this thing, you can find ways of rendering these creatures in a different light. And it's not that hard."
"The bulk of the design took about a year, solid. It’s because of the unique features of the dragon," he explained. "Early in production I came up with a very strong idea that would separate Smaug from every other dragon ever made. The problem was implementing that idea. But I think we’ve nailed it."
"I think one of the designs I'm the proudest of is Smaug. Obviously he took the longest. Early in production I came up with a very strong idea that would separate Smaug from every other dragon ever made. The problem was implementing that idea. But I think we've nailed it. I cannot tell you what it was because it would be a massive spoiler! But I’m 100 per cent happy with Smaug. If there is such as thing as 110 per cent, then I’m there!"
Goddamn. He says all the right things.
Now, my understanding is that while GDT had final say in the designs, the designing process was collaborative between GDT and Peter Jackson (along with Alan Lee, John Howe, and Mike Mignola). It being a collaborative effort, I'm assuming that they had thorough discussions about each design - what worked, what didn't, etc - and that each of them had input. So while GDT had the final say, I imagine that each final design was agreed upon by the two of them.
So if the design process was collaborative, how much will PJ ultimately change? Will we be seeing the new, majestic Wargs, or will we get the return of the Hyena-like creatures of TTT? Will we be seeing the "massive but nimble" Mirkwood Spiders, or miniature Shelobs? And above all, will we be see the groundbreaking Smaug which had our former director "110% happy", or will PJ opt for a different design altogether?
Honestly, I hope that the majority of GDT's designs make it into the final film. But I recognize that PJ is the director now, and he is not obligated to stick to designs that he may not be fully behind. However, at the very least, I truly hope PJ keeps GDT's Smaug 100% intact. Just listening to him gush about the design, hinting at a secret that has never been done before with talking dragons, makes the hair on my neck stand up. I truly believe that, more than any other design, THIS was the one that was going to leave us stunned in our seats.