You suggest that there is a natural cycle to such losses. But you ignore artificial interventions such as death duties.
Your futurism or modernism is nave. Not even Communism lost sight of the goal of culture to be enjoyed after industry - even if it failed to get there. You seem to envisage that work in a factory or an office is itself the goal. Or perhaps you believe (with Baroness Thatcher) that if you give people money they will realise they do not need heritage.