Maybe create a non-profit trust fund bank that will buy and hold capital assets to "back" BC. Change from mining free BC, to mining a right to purchase BC at half the current exchange rate, with the income going into the bank. Anyone could exchange their BC for their share of their current value of those capital assets (minus a 5% withdrawal penalty). Normally the price would float somewhat above the asset value - when it rises enough, allow the bank to directly create BC and use them to purchase more assets - locking in gains and at the same time keeping the exchange rate from rising too fast, reducing the impact of speculation.
Objections / alternatives?
And follow the same route on what fiat is going through right now? the non-profit trust fund bank like what you say could end up as centralized bank to control flow of bitcoin. In other words, open up the possibility for manipulation? No way. Let it be in a free market.