Another consideration: whether the entrenched players can simply make minor adjustments to counter that threat. For example, take your first point, filling out forms. It used to be you always had to do it. Then contactless payments took off in Asia. There was all this buzz about NFC and how it was going to disrupt the system and mobile carriers were going to get involved and so forth. So what did Visa/Mastercard do? They just relaxed the rules so that swipes under a certain amount don't require a signature. Poof, there goes the opportunity, because there's no way the cost of an NFC rollout is worth the extremely minor difference between a swipe and a tap. (Go ask Google Wallet.)

And so it goes for most of the technical issues, I think. Trust and security too.. you could make it easier on the merchant, but at the same time harder for consumers to recover funds if they "did something wrong" like installed malware.

Excited about the new frontiers into digital cash though. And also scared too. The biggest use case for bitcoin right now is not payments. It's international money transfers that skirt capital flight controls. And, for us non-libertarians, it ought to be a big concern. It's a profoundly anti-democratic force. It gives the wealthy minorities (esp. in third world countries) a veto power over policy. Don't like some new environmental or safety laws, or higher taxes to fund public education and health? Just transfer capital out of the country and watch it wither.