Here are my thoughts:
As far as I'm concerned, 3D is in. Graphic design includes 3D. Whether we as designers like it or not, it's here, it's becoming more and more common, and it's not going to go away.
Even if you think only of texture maps, there's a ton of graphic design in 3D work and an increasing amount of 3D in graphic design for other media than film or video. Many 3D looks that once took many hour of painstaking work in Illustrator or Photoshop can now be accomplished in an hour or less using Photoshop's built-in 3D features or even a lightweight 3D application like Xara or Sketchup. We can't say that the former is allowed, but the latter isn't. That is a completely artificial distinction with no place in the real world.
In the last 25 years the responsibilities of a graphic designer have grown to encompass typesetting, color separations and management, paste-up (used to be a separate hat, remember?), motion and interactive, web and mobile. As our tools become more powerful and the delivery systems for our work more sophisticated, we find ourselves pulled into these things by necessity and client demand. Economics dictates that we use the most efficient tool for the job, and if that happens to be a 3D tool, so what?
Graphic design today is a pressure-cooker of evolving technology and evolving client needs. 3D, like mobile, is a part of that evolution. As designers, we either embrace these changes or we embrace obsolescence. No apologies if that seems a bit over-dramatic. There really isn't a middle ground.
GD isn't about 3D modeling or animation, but the fact that dedicated 3D programs are mostly used for those things doesn't mean we must exclude 3D as a topic.
We -- designers in general and gd.se in particular -- have to be willing to embrace the technologies that get the job done. We are living in an era where we have to run as hard as we can, just to stay in the same place, and run like anything if we want to get anywhere. That's true for designers, and I can tell you from interacting with people inside Adobe that it's true for the companies who make the tools we use.
The Red Queen would have understood perfectly.