Is 3D printing a replacement for conventional production technology?

3D printing is not a large-scale replacement for existing production methods such as casting and machining. Its advantage is that it complements these other technologies where they cannot compete. For example, the additive nature of 3D printing is capable of creating structures that are not possible with machining or injection molding. Likewise, it's much faster to get started, which is why GM is moving to convert its production line to produce ventilators during the pandemic. 

It also makes small to medium volume production economically feasible as there is no need to invest in tooling. In short, 3D printing is a new tool in the toolbox, but one that offers significant advantages over traditional production methods.