And there really can't ever be one. A bank requires some way to offset risk (insurance, etc); If it gets robbed, the insurer pays out; In this case, an insurer would need to physically keep more bitcoins than the insured on hand in order to handle a payout situation. Since bitcoins can't be 'printed' like dollars, there's no way to simply have an 'FBcIC' without allowing them to substitute something for those bitcoins in a payout situation (e.g., the USD cash value).