I think asking people to put a value estimate on a thing is a hopeless task. The idea of having some sort of structured market for it is even more hopeless.
Better to just have a fee structure that starts off as the price of a carton of eggs and doubles every year that you extend it.
Would be profitable for Disney: they can value copyright highly because they have the expertise to value a work and also can shittify the work.
Not so good for anyone that cares about the artistic value - they are not economic specialists so they struggle to value a work and they perhaps don't wish to extract maximum $ from the work.
Bill Watterson was strongly opposed to merchandising calvin and hobbes, claiming that displaying images on commercially sold products would devalue the characters and their personalities. Bill's stance against commercialism is the main reason why the series never made it to TV or movies.
Forcing Watterson to pay fees until he loses all creative control over his works seems controversial.
Better to just have a fee structure that starts off as the price of a carton of eggs and doubles every year that you extend it.