I think it's completely fine to renege on deals that were made with people who have been dead for centuries, actually, if there's a good reason to.
Courts and political institutions routinely nullify all kinds of "deals" that are considered to be against public policy. For instance, lots of people in the US made legally binding deals to purchase other human beings as slaves, and those deals were undone by the 13th amendment. Maybe those people would have made different life choices if they knew that their slaves would be freed in the future. Tough luck.
Courts and political institutions routinely nullify all kinds of "deals" that are considered to be against public policy. For instance, lots of people in the US made legally binding deals to purchase other human beings as slaves, and those deals were undone by the 13th amendment. Maybe those people would have made different life choices if they knew that their slaves would be freed in the future. Tough luck.
In other legal contexts, we recognize that allowing people to exert control over things long after their deaths is a bad idea: https://en.wikipedia.org/wiki/Rule_against_perpetuities