Difficult question.

In 5-10 years, 3D printing will be in direct competition with virtual reality. But virtual reality is already offering near full immersion experience and it isn't even in the public market yet. VR does the obvious visual and audio portion, but it also allows finger and hand movement with the Myo, full body movement with the Kinect, and even smell (immature), taste (immature), and haptic feedback (immature). Google is working on Project Loon which will distribute the internet around the world via low flying satellites/airships. Google is also working on Project Tango which will let people project their physical surrounding into VR. VR technologies will advance dramatically over the next five years because the market will be ginormous and there aren't too many technological hurdles in the way.

3D printing, on the other hand, will largely benefit innovative industry projects such as the GE/Local Motors collaboration in FirstBuild. Personal printing, on the other hand, may not develop too much over the next five years, though hobbyist contributions will be significant. By the time personal printing goes mainstream I think the FirstBuild collaboration models will have spawned into open source developer communities to address almost all retail industries.

Virtual Reality with hand coordination provided by devices like Myo will make 3D model development much easier. It will become common for people to collaborate in a virtual environment to design useful objects then distribute them for free. In addition, pirating will be common practice. Consequently, Shapeways is a short term trinket/gift site. Cool stuff, but no big growth. Thingiverse is ok too, but they will be overrun by independent communities with established reputations in specific product lines. Therefore, a multibillion dollar 3D model market, in my opinion, will never develop. It will exist, but the models will be free.

3D printing is a money printing machine, but so is virtual reality. The difference is that virtual reality is going to provide more bang for the buck in the short term so that is where the retail consumers will gravitate.