When 3d printers break the 300 dollar mark, we'll have, like the author noted, a whole new argument over digital rights. And GW will either have to adapt or cease to sell models. Imagine if they could sell the designs, so that you could print your own 'legit' GW model.
We already see this in America, where GW places a good deal of demands on their independent retailers and in the officially sponsored events. Models must be X% GW material. Models must conform to rules A, B, and C.
I could easily see GW selling the designs, implementing some sort of mark (which they could copy right and circumvent the patent issue), and saying that in order to be included at any official event, the model must bear that. It wouldn't be perfect, and there'd still be those who found ways around it, but, it could work.