The next episode of 3D printing will involve printing entirely new kinds of materials. Eventually we will print complete products - circuits, motors, and batteries already included. At that point, all bets are off.
If you gave kids peas that didn't look like peas and said they were a space shuttle, they're much more apt to eat them because it's now playtime.
3D printing is already shaking our age-old notions of what can and can't be made.
When it costs you the same amount of manufacturing effort to make advanced robotic parts as it does to manufacture a paperweight, that really changes things in a profound way.