Trying out variants of older approaches would probably work, though; a system which grants a short (say, 14 or 28 years, like the old terms were) term of copyri

Trying out variants of older approaches would probably work, though; a system which grants a short (say, 14 or 28 years, like the old terms were) term of copyright automatically, but requires registration to extend the term beyond that would solve the orphan-works problem, and allow people who really wanted to maintain copyright on their old photographs to just batch-register them at the extension date.