How this will effect GW?
Lowers the cost of entry to producing miniatures. 3D sculpting has exploded in just a few years and a lot of that has to do with 3D printing. There are combo units coming out that are scanners and printers in one system. Drop in your Marine sprue, scan and then print.
I think the biggest threat to GW is that this allows smaller competitors to create figures and produce them in numbers that they wouldn't have been able to before. It also opens them up to sculptors who may be geographically distant but able to deliver figures digitally. Look at the number of companies producing everything from 6mm to 54mm figures in a range of genres.
At the moment, outside of terrain and tokens I don't see myself printing anything gaming related but the growth of companies working via 3D and 3D printing keeps getting bigger each year.
Take Secret Weapon miniatures for example. They designed and are producing 3D sculpted terrain boards similar to the Realm of Battle boards that GW did. A small company with a digital sculptor sends 3D files to a manufacturer who builds moulds and then creates hard plastic terrain tiles.
Suddenly GW has competition in a very expensive market from a small company that wouldn't have been able to do this five years ago.
GW is a big player in a very small market and when your smaller competitors can suddenly scale production to meet yours you have issues.