I am with pitaj here, intellectual property is fundamentally wrong, but this is a good example of something that I'm not sure would work under no copyright. "Pay what you want" is one way, though I don't have any statistics on if that collects enough money. Another could be selling signed copies or otherwise making some copies exclusive in a way that copying them nullifies. Pay what you want + signed copies + patreon style donations might be enough?

I don't have a good answer to this. I would therefore suggest decreasing the duration of copyright to somewhere around 5-10 years to give the copyright holder time to sell the work with exclusive rights, after which the work enters public domain (like copyright was initially intended to work).