Legislators could just offer a very easy solution. They could simply mandate copyright holders to offer the copyright to all interested parties at a fair price. If content ist held back or only exclusively distributed through one party it should go public domain, as the holder of the rights clearly does not intend to profit in a legitimate way from.

The intend of copyright is to make sure, that the holder of the right can get a fair compensation. It is not the intend that his work is abused to manipulate the markets.