> I'd want some way to coerce companies into making physical media but I'm not sure that can be done.
Don't worry about physical media. Formats come and go. In order for a company to have any copyright protections at all on a work, a high quality digital version should have to be submitted to the copyright office which should automatically make that copy available at copyright.gov the instant the copyright on the work expires. Any edits or censored versions a company puts out later would then need to be copyrighted and submitted to the copyright office separately making sure that the originals are always preserved and available.
Don't worry about physical media. Formats come and go. In order for a company to have any copyright protections at all on a work, a high quality digital version should have to be submitted to the copyright office which should automatically make that copy available at copyright.gov the instant the copyright on the work expires. Any edits or censored versions a company puts out later would then need to be copyrighted and submitted to the copyright office separately making sure that the originals are always preserved and available.