This is the message I do not want to see on Sony's ebook store
http://musicstore.connect.com/
I think with the existing hacks for uploading content to the Sony Reader, the Reader will continue to have a life for a long time (I still use my minidisc players), but I would not recommend buying a lot of Sony DRM'd books.
I would hope that Sony would provide a mechanism for reformatting their DRM'd books (making them useful after your Reader dies) if their Reader was ever discontinued. But based on my experience, that ain't gonna happen.