Rather than demonstrating that you are profiting from the work (which seems a low bar to clear), a sliding scale might be a better middle ground. Something like

Rather than demonstrating that you are profiting from the work (which seems a low bar to clear), a sliding scale might be a better middle ground. Something like (years for illustration only; personally I'd probably go for shorter terms): - 0-20 years post publication - free, automatic protection (i.e. basically what we have now) - 20-30 years post publication - nominal fee and continuous (yearly?) registration required to maintain protection (to prove active use/interest) - 30-40 years post publication - large-ish fee and registration required (most works would probably be 'abandoned' to public domain here unless continuing to be commercially successful or backed by a large corp.) - 40+ years post publication - increasing fee each year indefinitely. Disney et al. can keep major works protected if they wish, but most works will enter the public domain