@OP

As someone mentioned, there is no reason for a rational user to risk dealing with a fractional reserve bank with Bitcoin, unlike with gold. All it takes is one bank publishing 100% transparent blockchain data about accounts in custody. Then who is going to put up with fractional reserve?

Central bank? Inflation via derivatives? No, Bitcoin can't be centralized and dissolves the government power necessary to enforce the perverse incentives that created the present fiat money derivative situation.