It would be really great if the companies who are doing this would commit to placing the scanned files into a public trust that would coordinate with organizations like the Gutenberg project to ensure that the scanned materials enter the public domain on schedule. Publishing encrypted archives with the keys in escrow would be a good first step.

IMO that would go a long way to resolve any concerns about losing books. I still don't like the idea of extremely hard to find or last prints being actually destroyed for this, but it certainly makes it more palatable.