Some of the main questions when it comes to 3D printing are: what scale will it reach in the future? Are we going to 3D print whole houses, and would that be efficient? Maybe not on Earth, but what about the Moon? Investigations are being carried out on how sensible and sustainable it would be to print a whole house, and the inspirations behind that are strongly connected to the availability of moon dust which can potentially be used for 3D printing structures on the Moon (see printing with sand by Enrico Dini below).
Speculating about the scale and impact additive manufacturing will reach in the construction industry - a likely outcome is fabricating elaborate structural parts in factories and assembling them on site, as it will be costly and time-consuming to move large 3DP machines between different construction sites, and inefficient to try and print whole houses with the technology available currently.