I don't think that temporary part fabrication for critical assembly lines qualifies as overhyping 3d printing. That seems super reasonable :) A 3d printer in every house, completely removing the need for centralized manufacture or distribution, a bit moreso.
So, there was this factory. A part broke, it would take 2 days to get the part from the supplier, but the whole line was dependent on the machine. They had a laser scintering 3d printer. they made a poor quality, but good enough for a few days use replacement. I think it was a broken tooth on a cog, the kind of thing that would be tough to mill without some decent expertise on hand.
In any case, i think that's more or less the future usage. If things are worth repairing, any parts made after the initial run would probably just be printed off. Pretty easy to imagine in a utility truck, or auto part warehouse.