A simple approach is to apply the "intellectual property" analogy consistently - and that means taxing it like we tax real estate.
You could have a short grace period - say, a couple of years - with no tax at all, to accommodate individuals and startups exploring a market etc. After that require explicit registration for continued protection, or else the work automatically falls into public domain. And anything on the registry is taxed.
Furthermore, said tax could be made progressive, to discourage copyright hoarding, and impose a natural term limit. More valuable works would have longer-lasting copyrights with such an arrangement, but there'd always be some point past which it's simply no longer profitable. No abandonware, either - if the tax isn't paid, it becomes PD.
You could have a short grace period - say, a couple of years - with no tax at all, to accommodate individuals and startups exploring a market etc. After that require explicit registration for continued protection, or else the work automatically falls into public domain. And anything on the registry is taxed.
Furthermore, said tax could be made progressive, to discourage copyright hoarding, and impose a natural term limit. More valuable works would have longer-lasting copyrights with such an arrangement, but there'd always be some point past which it's simply no longer profitable. No abandonware, either - if the tax isn't paid, it becomes PD.