Legal Question in Intellectual Property in California

My advice would be to tread with caution. While copyrights do expire, and the rights become public domain, this is not coterminous with the company going out of business. With sports cards, someone is pretty likely acquiring and maintaining the copyrights as the original publishers fall by the wayside. Since you are thinking of self-publishing, you won't have an editor and publisher to handle researching copyright status and getting releases where needed, so I strongly recommend developing contacts with one or more copyright attorneys with whom you can develop a working relationship. They may not charge you that much and your issues may be relatively simple compared with what to do with a garage full of newly-printed books you can't sell because of infringement suit threats.