Yes, you can print all the cheap low-value add things we currently outsource to China and other low-wage countries, but you can also personalize them.
That's a potential recipe for major disruption.
I can get a personally engraved iPod in a startlingly short period of time.
Lean manufacturing has been pushing towards the idea of pushing different things off the end of a production line for years. They'll carry on doing that. As the technology improves they'll integrate 3D printing type technologies into the supply chain.
Personalisation is certainly interesting - game changing in some instances almost certainly.
That doesn't mean that it's going to happen via 3D printers in your home. I find it hard to think about any kind of personalised object that I'm going to need urgently enough to print now gosh darn it, rather than wait for next day delivery. Especially at the ongoing cost of another box taking up space in my house.
I might have one coz I'm a sad techie who loves fiddling with stuff... but that's not a mass market. That's in the order of magnitude of the home-CNC machine/lathe market.
I can imagine technologies that might hit a mass market. For example if printing and disposing of kitchen mugs / saucepans / cutlery / etc. becomes cheaper/easier/smaller than buying / storing / washing them up then I'd buy a 3D printer like a shot. That kills a major pain point for me. But nothing like that is even vaguely close.
I've yet to see any problem that will persuade 'normal' people to get a 3D printer in the home that's anything close to an implementable reality. I'd love to get educated if I'm wrong ;-)
There's Costco's bulk lots and then there's manufacturers's bulk lots :-)
The economies of scale in producing the raw material will likely mean that its price will drop a bit, but the guy buying 5 tons a month will always get a much better price than the guy buying 5 lbs a month. Even if there are 50 million guys doing the same thing.
The price each individual pays approaches that of the manufacturer, enough to make this a viable alternative. This is nothing new.