It's one thing to require the copies in order to register the copyright and gain the legal protections afforded by that, but it's another thing entirely to start threatening to fine someone for NOT registering.
I agree, I'm sorry I didn't make that clearer with 'going to get' being that doing so would be voluntary, but if you want copyright protection you have to do it.
Back when I was first proposing it, the internet was present, but low bandwidth and cloud storage a dream. But even then I knew that digital was the thing. So for written works I wanted them in an unencrypted standard media format. Think PDF, but I wanted to include the formats used by the major publishers to run their printing systems. For movies and such, the DVD glass masters. Painting? A high definition digital scan at least. Music/Recordings? A lossless high definition recording(or at least the best you have), Etc...
And I'd set copyright to something like 20 years, extendable for a reasonable fee that would go towards storing all this stuff and eventually make it all accessible. The first "Free" with the submission of the archive quality copy, but after that you pay storage fees unless you want to release it to the public, copyright expired. I'd have the library of congress able to charge for access, preferably a cheap subscription model, which pays to keep the public domain stuff accessible.