That is not an easy question to answer. The approach you suggested is certainly one that could be considered. You mention that most people would sell those shares for cash.. well that is cash in their hands then. That is money they didn't have before that they now have, that they can then spend on goods and services correct? Is it not redistribution of the wealth of the deceased within society?
It sounds like you agree with the principle, but are worried about the implementation. I would likely consider myself to be in the same boat. However, I am not even seeing any public conversation about it, or an attempt to move in that direction. I think the conversation should be
"This is what we want to do, this is fair wealth redistribution.. now let us come up with ideas on how we can make this work".