nice idea in principle, shame about the impracticability

The problem is that even if the author refuses to make a copyright claim, her heirs gain control after death and can certainly make such claims. Copyright terms are explicitly beyond the authors death and the one that inherits that claim may not be as generous as the original author.

It's interesting that I haven't seen a comment explaining that GPL was specifically designed to use copyright _against_ copyright. That's the entire concept behind copyleft. As copyleft grows in time it's not inconceivable that copyleft will replace most commodity software and in the process destroy much of the copyright regime in software.