sure it's a long way off, and just the material to print a disc would probably cost more than just buying an OOP disc. Of course if you printed a downloaded mold you could be gotten for piracy! I think I'll go gbuy the domain name disctorrents.com for in the future when this is a reality!
Piratebay is way ahead of you.
Printable Shoes?
I think that probably ten or twenty years in the future that some startups will manufacture prototype discs this way. They may even be able to make production runs this way, depending on how expensive the resin is to fill the printer. But I think that production discs will be created much the same way they are now for the foreseeable future.