The design always included replication of the content. When information is originally published, you can request that "n" copies are sent to other back-end hosts that are advertising they have available storage. I believe we intended n to be at least 3. In addition, when someone requests content that is not already available locally and especially when they transclude the content, the back-end they are using is encouraged to make a local copy. So that answers "what if the linked host dies".
All content is already copyrighted by the author(s), and in order to publish it on the Xanadu network they have to agree to publish it under transcopyright which grants prior permission to transclude it. That does not preclude also offering the same content elsewhere under different license terms, but revoking the original license agreement would require the content be removed from the Xanadu network. IANAL but I suspect people might have some rights to rely on the original license unless properly notified that the rightsholder had revoked it.
All Xanadu content is append-only versioned, so if someone gets hacked and content is changed, nobody is obligated to transclude from the altered version. They can continue to transclude earlier versions.
All content is already copyrighted by the author(s), and in order to publish it on the Xanadu network they have to agree to publish it under transcopyright which grants prior permission to transclude it. That does not preclude also offering the same content elsewhere under different license terms, but revoking the original license agreement would require the content be removed from the Xanadu network. IANAL but I suspect people might have some rights to rely on the original license unless properly notified that the rightsholder had revoked it.
All Xanadu content is append-only versioned, so if someone gets hacked and content is changed, nobody is obligated to transclude from the altered version. They can continue to transclude earlier versions.