Well, it will make it possible to make replacement parts for household items by starting the printer before going to work and coming home to the part all ready for attachment. 3D scanners already exist for working up the CAD.
I am sure that you know what consumer quality 3D Printers are currently capable of more than I do.
I recently purchased a used carpet cleaner at the Goodwill. I had to pay $30 with shipping for the parts I needed to get it going. It probably would have been possible to make a few of the parts with a 3D Printer, but I am not sure how much trouble it would have been and if the parts would have been durable enough to actually hold up. The originals broke and they were designed by people who knew what they were doing. There is sometimes more than just making a plastic part the same shape as the original involved in making a replacement.