>>joseph+(OP)
So, if the publisher changes a single word in a new copyright, and the old one expires, can the publisher sue someone who shared the old version? It'd only be one word off, so they could argue it's effectively infringement...
>>detrit+I21
No. If that trick worked, you'd have seen it happen to at least one extremely popular public domain work (e.g., the King James Bible) by now.
>>detrit+I21
They could make that argument, but wouldn’t succeed (speaking from the US legal viewpoint, anyway). The only copyright held by the publisher would cover the additions and changes; the original work would no longer be copyrightable.