It would separate two forms of money: the common form of money used as means of exchange and a store of value; and, the debt/credit money created out of thin air through a contract and collateral. The two currencies would float against one another. People would be paid in common currency, but could borrow in the debt currency.
Forget a new kind of bank. Go total bluesky. What IF, we could design our own set of sovereign laws and principles.
What would the "modern" country look like?