That's precisely the same as an uncashed check - an IOU. Just because you can cash it at any time does not make it different from an IOU. Until settled, it's

That's precisely the same as an uncashed check - an IOU. Just because you can cash it at any time does not make it different from an IOU. Until settled, it's just a "hey I will pay you some Bitcoin in the future". It's a commitment to a payment that untrusted parties are going to settle immediately for reasons discussed above.