This seems like a bad idea to me. It seems like it is a feature that might be desirable for speculators and others who like high volatility. Thirteen weeks seems like a short time to me relative to traditional investments, not a long time. My understanding is that an aspiration for the Steem blockchain is mainstream adoption, and I think features which favor volatility and speculation work against that. Additionally, people who don't want their value tied up behind the powerdown window already have a solution: liquid steem. Why do they need a second one, at the expense of all the risk this change poses to the economy?