And then one day they pull out Walt Disney's frozen head and claim he isn't really dead. No a fixed term is the only thing that makes sense. Postumus publication would still get a full term of copyright.
Or we can just junk the whole system and start over
There has grown up in the minds of certain groups in this country the notion that because a man or corporation has made a profit out of the public for a number of years, the government and the courts are charged with the duty of guaranteeing such profit in the future, even in the face of changing circumstances and contrary public interest. This strange doctrine is not supported by statute nor common law. Neither individuals nor corporations have any right to come into court and ask that the clock of history be stopped, or turned back, for their private benefit. That is all.
Robert A Heinlien in Life-line 1939