Honestly, merely limiting drastically the maximum copyright term would probably cover it. (Not just by making things public domain more rapidly, but also by presumably providing pressure on the business models of companies currently relying on the existing duration of copyright.)
Back in 2006, the UK commissioned a report recommending how to revise the copyright system (the Gowers Review of Intellectual Property), and it particularly recommended against any further increases in copyright terms - contra pressure from the music industry - and essentially only didn't argue for decreases because of international obligations. On pages 52 to 55 of the Review, however, there's quite a lot of evidence suggesting that most producers of creative works would not be meaningfully harmed in earning power if the term of copyright was as short as 10 to 20 years after production.
A 10 year copyright term, renewable for a further 10 on application, would do a lot to redress the balance you mention here.
Back in 2006, the UK commissioned a report recommending how to revise the copyright system (the Gowers Review of Intellectual Property), and it particularly recommended against any further increases in copyright terms - contra pressure from the music industry - and essentially only didn't argue for decreases because of international obligations. On pages 52 to 55 of the Review, however, there's quite a lot of evidence suggesting that most producers of creative works would not be meaningfully harmed in earning power if the term of copyright was as short as 10 to 20 years after production.
A 10 year copyright term, renewable for a further 10 on application, would do a lot to redress the balance you mention here.