Tighter iteration loops does seem like an area where startups could help. Maybe not just with 3D printing, but in other areas of coordinating the workflow as well.
I wonder too if there's some streamlining to be done in the supply chain. Look at how Amazon streamlined retail to a point that they serve not only as a catalog/payment service, but also a fulfillment house. Is there something like that to be done with supply chain? Manufacturing?
I know there's companies out there in those areas, but that doesn't necessarily mean there's not still big gains to be made somehow.