The nature of the products GW produces makes them prime candidates for home/local reproduction.
As the technology advances to the point where qualities between store bought and home produced items are near/the same, business models will have to change, especially if the items can be printed for a fraction of retail costs.
The consumers thought process at that point becomes: "if I can make this product for a penny, so can the company that is charging me a dollar."
If/when the company refuses to change, the math/decision making process becomes fairly easy.
I agree that retailers will suffer, which is unfortunate. But, as with all other significant advances, you have to integrate them into your business (large or small) to succeed.
Adapt or die. /shrug.
Still pretty far off time wise, but on its way with this particular technology.
I don't think it will destroy GW or other smart retailers, but I do think it will change them. Hopefully for the better :)