They could revert from public domain if the push for prolongation to life+90 goes through before 2014, but that should not be affected by who holds the actual papers. A vote for PES is a vote for EPP! A vote for EPP is a vote for PES! Support the coalition, vote EPP-PES in 2009!
This matters because specific publications are sometimes edited, making them slightly unique. Although I can download a copy of something by Jane Austen from one of the archive sites on the web, I can't legally scan and upload a particular printed version. Similarly if I translate something by Plato into English, the translation remains in copyright, even though the original Greek is in the public domain.
I can't see how it's possible to prevent a performance of the music on an old manuscript, unless the manuscript was stolen. The owners own the manuscript. If the music on it is already public, it remains public. If it wasn't public and was copied without permission, they have a case of sorts based on the loss of value of their original, but it's not quite a standard copyright case.
As I see it they have two options, either publish the original text as it is, meaning Kafka is the author and it is public domain or publish an edited version which - as TBG points out - means that the total version runs under the editors copyright (life+70). But to prove that it has been edited enough to warrant copyright they will need to release the original, which will then be in public domain. Unless there is some legal way to prove without the text becoming public.
In the german case I wonder how the would-be performers got the copy in the first place if it is unpublished. A vote for PES is a vote for EPP! A vote for EPP is a vote for PES! Support the coalition, vote EPP-PES in 2009!
