If 3D printing successfully usurped every kind of manufacturing at every level what would the world look like? What tasks would take on greater importance? Well, even if you can just make anything in your own home in short order, you still need to know you're making the right thing, so you need the skill of requirements analysis. What job is this piece supposed to perform, and is it fit for purpose before I go and manufacture it? You also need the skills to install or assemble and maintain what you manufacture. How do you use what you've made? That's not included in manufacturing. Finally, if you can't find the exact ready-made design to fit your needs, you need the skills to produce it from the ground up, including the materials knowledge to decide from what it should be made. Is this a job for ceramics, or plastics, metals or something else?
Mokalus of Borg
PS - In short, even ubiquitous, all-encompassing 3D printing won't solve all our problems.
PPS - As with most technologies, it just shifts the problems higher, which can still be a good thing.