This is going to be interesting. I suspect there will be a middle ground found. We already have laws regarding copying someone's design. The question will be around "fan" work, and the ability of folks to be able to check for copyright and patents easily. AND, it will be up to the copyright/patent holder to hire lawyers and take people to court. So, if you don't have the cash, you won't be able to defend yourself from people copying your design.
And once the 3D printing designs are out on the Internet, it is going to make it even more challenging to protect your own designs.