Re: Interesting.
This is kind of long, be warned. 3D printing has a ways to go to reach parity with the accuracy of CNC machining and will likely never meet the precision levels of traditional hand machining.
Higher end Commercial 3D printers can reliably output to about .0005 but beyond that their output falls off exponentially. Even with optimized instructions they are also terribly slow compared to a CNC machine. 3D does seem to offer a lot in the way of new processes and design options but there are a few challenges be for you see them in the mainstream.
Product design as well as manufacturing is built around established 'subtractive' processes that have been proven at scale for 100+ years. Changing those mindset a won't happen within a single generation. From raw materials to a finished good is an incredibly complex and established system and is profitable only if every step and person in the chain is optimized for maximum output. The primary reason I employee software developers and a computer scientist is for optimizing small production runs through the CNC. Each step that can be eliminated and each minute saved on the machines translates to hundreds of thousands of dollars throughout the year and we're a small operation specializing in bespoke parts for extremely specialized uses. In a mass production facility changing 10 generations of proven best practices is going to take a while.
There's no infrastructure to support 3D manufacturing at scale. From trained machine service techs, to materials supply chains and billing systems, they all have to develop and it will take a while for that to happen. There's also no scale and quality provider of all the different tooling needed. Although we can make about anything it isn't cost effective to produce things like hold downs, vices, waste removal systems, etc... I've got to have a steady supply of lots of little things and those little things are completely different in a 3D environment. In an emergency I can send our plane to a supplier and get exactly what I need in just a few hours and that's normal in the industry. There are no 3D suppliers yet that are equipped to deal with that and a million other things.
There's no real standardization in raw materials yet. From the actual materials, their transport processes, waste disposal even materials handling: Will the containers of raw materials be compatible with the tine setups on my fork lifts and cranes? Who is responsible for empty containers? Will the containers be compatible with the rails and belaying systems in my railcars or do I have to buy new railcars? If so who is going to design the railcars?
There are a whole host of other issues as well. That isn't pouring rain on anyone's parade, it's the reality of inserting completely new things into large, well established processes, it will take a while. There's also lots of opportunity for enterprising individuals to set up all the infrastructure... People take for granted how incredibly complex manufacturing is. You can't just plop a machine down in a factory and expect anything to happen without thousands of other people doing specialized tasks before you even turn the machine on.
Within my industry there is pretty much agreement that 3D printing will eventually operate in parallel with CNC, but won't supplant it as there are advantages to both. But 3D is a very immature industry and it will take many years of solving operational logistics and standards issues to reach the mainstream.
And as far as extreme precision, that will remain in the hands of the traditional machinists and their traditional tools and machines. There's general agreement that an entirely new form of technology (think replicators) will be required to go beyond the levels of precision achievable now with hand work. We've got the finest CNC equipment money can buy and a starships worth of lasers (one big enough to put a car in) and none of those things can really approach the old school methods as far as tolerances go. Not many things really require or benefit from those levels of precision* which is why CNC has been a success and 3D defiantly has a future in the industry.
*We can work down to a few millionths of an inch if required and automated machines simply can't do that, there's just too much slop in them. The work runs into the many thousands of dollars per hour and individual components take days or even weeks to make but sometimes it's required. Among other things we design and manufacture laser positioning devices for high energy research experiments that have tolerances so high that the finished goods are hard to look at. Things that precise simply do not exist in nature and it's a little unsettling to see something like that. It simply looks unreal, like it shouldn't be in this universe. It also puts the general sloppiness of the natural world into perspective. It helps me to remember that most things aren't perfect and it's unrealistic to expect them to be.
** As a fun side note, I have a tungsten table I made for my office and on top of it sits a six pound tungsten weight, both finished to .00001". The surface tension from the moisture in the atmosphere and molecular entanglement between the two surfaces make it so that it requires a stronger than average person to lift the six pound weight from the table. People think they're magnetized, but no, they're just flat. Really, really flat.