Personally I dont think 3D printers will ever be an "Everyone" machine, like a PC is. You still need a bit of understanding of how computers, drafting, and the mechanics of the machines to get any use out of them. I could see it being the difference between a screwdriver and router table.
Damn near everyone will have a screwdriver in their home, but only hobbyists spring for a router table. If anything I can see printers being setup in shops like Kinkos where people can take a design and have it printed in an afternoon.