3D printers capable of working with metals will NEVER be "dirt cheap".
Crude devices extruding plastic and/or photopolymerizable polymer precursors are the only types that will ever be "dirt cheap".
3D printing will be used where it has advantages, just like every other technique of manufacture, but it is just another tool. All this hyperventilation about "3D printing will change the world" is just silly.
3D printing certainly offers many opportunities for improving things, but it is NOT a panacea.
3D printing certainly offers many opportunities for improving things, but it is NOT a panacea.
Yet.