So let me think about this... It's difficult for me to guess without first seeing the code, but let's imagine it is possible to create a directory and then subsequent directories from then on... this would allow the client to archive each newsletter, yes?
Let's say we have a generic home page at root_index.php on that page would be a little design and some wording stating "Click HERE to see latest Newsletter" This would then take you to a subdirectory
root_index.php/summer2010/index.php and all the sub_linked pages would reside in this directory - root_index.php/summer2010/article_01.php
Now - when this news letter has expired the "Click HERE to see latest Newsletter" links to a different directory root_index.php/autumn2010/index.php
and all it needs on the home page is a further div adding:
• Click HERE to see latest Newsletter
• Click here to see Summer2010 edition
This extra link would be created after the second edition is live and thereafter my client only has to add other archived links on the home page.
This solution would work if it was possible to create whole sub_directories in PowerCMS
Let me know about this