A variant where the copyright would be automatic but very limited (say, 10 years), with a necessity to pay some growing fee for extended protection, would solve

A variant where the copyright would be automatic but very limited (say, 10 years), with a necessity to pay some growing fee for extended protection, would solve most situations. The vast majority of stories do not make any money ever. Some do, but only briefly so. The true money makers should have no problem paying the fees. Only very rare cases of authors who get discovered decades later would not be covered by this, and this is less likely to happen with the Internet. There are no publishing gatekeepers anymore.