And why can't they have a license that simply says: "10 years after the publication date, this work will enter the public domain" And in countries where they d

And why can't they have a license that simply says: "10 years after the publication date, this work will enter the public domain" And in countries where they do not have a concept of public domain, simply change the royalty to 0 after that period of time. Or, simply say, after 10 years, you'll also be permitted to do x, y, z with this work (where x might be redistribution, derivatives, etc). At least in the US, authors have the right to do this today.