The sandbox supports the central banking 'ledger system' without bias. It will exist, and mostly be the dominant pricing unit. But it competes with the block chain, gold deliveries, and the null service. Why would it remain? It has this great utility of connecting the voter to the cost of the vote.
It will be clear to voters when prices are multi-currency. If 65% of the price is constrained by government guarantees, then we know it, we know when our price clubs reach the limits of conspiracy, the government gets its cut.
The new trend
Consider the household buyers clubs. They keep on plotting and working up the supply chain, up to very specific menus, bought wholesale and they get government out of the deal. In the balance, we get the complexity of home production increasing and the congestion in our streets decreasing. The buyers club will always return that to managed congestion, and they will accept government on its merits. The merits are finite, positive likelihood. The sandbox finds that balance.