Can you solve it? The mystery of Portia's caskets

A Shakespearean riddle in memory of peerless puzzler Raymond Smullyan, who died last week age 97

UPDATE: The answers and explanation are now posted here

"Why should I be worried about dying? It's not going to happen in my lifetime!"

So said Raymond Smullyan, the American mathematician, philosopher and prolific writer of logic puzzles, who died a week ago aged 97.