One obvious way to tighten such loopholes would be to ban indefinite licenses. It is either permanent or has a fixed, stated term. A permanent license must either entail no DRM or the entity must have a trust/endowment in place to ensure availability until copyright expiration. Copyright is contingent on a DRM-less version being placed into escrow for copyright expiration. Failure to ensure availability of a permanent licence allows access to escrow as recourse.