I watched a video that made an interesting point, that GW is moving away from being a model company into a larger media company like Star Wars or Marvel. There is more to the 40k IP than just model kits, they have books, games of video and board varaity, a full on animation studio now, probably a few films in the works, Funko and Bandai models, and if they're smart replica toys and costumes for kids.
So while I agree 3D printing can be a threat, GW may have decided well they can't stop 3D printing as a technology, nor stop dudes printing space marines, so fuck it, don't bother, make official GW space marine Halloween costumes and get a cinematic universe going.