I don't get why this is all so complicated.
Warners' copyright is supposed to last X number of years, after which it reverts to the estate. Congress extended the value of X twice in the past.
Hence, when those X years is reached, it all goes back to the estate.
What am I missing here? Have we reached X years?
If no, sorry estate, you have to wait longer
if yes, sorry Warners, your rental of the Superman property has run out.