Concern #1. Are individuals likely to honor each other's IOUs?

Concern #2. Are gateways likely to honor each other's IOUs?

Concern #3. Is there enough incentive for users to use this system over other services out there that already allow people to exchange fiat for crypto and vise-versa?

Concern #4. Is there enough incentive for companies to want to use this system, rather than just doing this on their own? If you are a company wanting to start a gateway, are your IOUs going to be valuable until you get other gateways honoring them? Are people going to be able to take your IOUs and use them to get other currencies?