The commercial 3D printing industry will surely outpace the at home 3D printing industry. Advanced tech costs. Home printers will always be around and they will improve. Makers will have the ability to create some amazing things off of a single print with multiple materials. However commercially, I expect 3D printing will be integrated into many industries. Sometimes as rapid prototyping tools, but I expect 3D printers to be used for more traditional manufacturing more frequently as well in the future.

Amazon took a Walmart type shopping experience online and then distributed it (they use dropship facilities across the world to be able to ship shorter distances and deliver faster). I expect the same thing will be done with manufacturing (to an extent) -- possibly by Amazon again.

I also foresee 3D printing becoming integral to the classroom for sciences and probably integral to a school in general for teaching materials.