What incentives do Crypto 2.0 systems provide for IOU Gateways?
Universal

In most if not all Crypto 2.0 systems, a Gateway can:


Charge the users for IOU deposits
Charge the users for IOU withdrawals




Ripple

In Ripple, a Gateway can set a percentage fee for whenever their IOU is transferred from one user to another. Say, at 1% fee, to send someone $100, one needs to spend $101. The recipient receives $100, while the Gateway's liabilities decrease by $1, giving them that much in profit.



Ethereum

In Ethereum, a Gateway can create an arbitrary contract for how its currency will be used. This contract can include any fee for currency being transferred or exchanged, demurrage, or anything else that can be coded in a smart contract.