It's about having your supply chain as close to your customer as possible so you can pull (as in lean) on demand. What then happens is the customers' needs iterate faster and faster and you need to keep up. Fit the 3d printer in the shop, print whatever the consumer needs in less then it takes to drink a cup of coffee and you're the winner. Of course you need to make sure you have enough raw materials. That's something China has to import a lot. So unless China builds up domestic demand to much higher levels, western countries will gain more from 3d printing than China.