Originally Posted by HarryT
This has nothing to do with DRM - it's simply a matter of differing, incompatible file formats.
It's no different to many other fields. If you buy an lens for a Nikon camera, and in 5 years time you go out and buy a Canon camera, you won't be able to use your Nikon lens with the Canon camera.
I don't think your analogy rings true - an e-book replaces a p-book. A p-book is still perfectly usable after 10 years, but an e-book may not be, because of lack of standardisation on file and DRM formats.
To use your camera analogy, I would expect the pictures produced by a digital camera to still be viewable after 10 years.
Also, if I buy a cover light for my PRS505, and in 5 years time I go out and buy a PlasticLogic reader, I would not
expect to be able to use my Sony cover light with my PlasticLogic reader. But I would expect the media (ebooks/pictures) used by the device (reader/camera) to still be accessible. If fact most digital cameras will happily load pictures taken on other cameras (e.g., using jpeg format). You cannot say the same about e-Readers.