I got an email from the IDSA yesterday saying to come to the Nat'l conference to hear Grace Bonney speak about DIY. Not knowing who Grace Bonney is, I went to her blog called Design Sponge. Its a nice blog about shopping, color trends, and how to sew and build things for your home or apartment. There was a neat set of illustrated instructions on how to make a bedside table out of an IKEA chair. From what I gather from this, DIY is a new way of saying "I do crafts", which my mom was doing and selling at bake sales 30 years ago. So rephrase the question: Are "crafts" a threat to industrial design?
On the other hand, the growing RP/3D print/upload-and-we'll-build-it world is very interesting, but I don't see that supplanting the bulk of what designers do either. Its like there are avenues that are somewhat new and interesting as movements or offshoots - and then there's the thousands of the rest of us who have to show up at 8AM and do solid modeling.
A side note: Designers may have black turtlenecks, fun eyewear and colorful sneakers; crafts (oops I mean DIY) girls have their own look too: natural, nicely messy hair; fuzzy wool sweater; cat or cats. http://www.designspongeonline.com/about