That's not really true. You can store Bitcoin keys on paper with QR codes (or even just in your brain), and sign transactions on devices that have never touched the internet and never will. It's just the infrastructure that hasn't been built yet, but there is a lot of development going on to enable the average user to utilize these possibilities. That's not even mentioning multi-signature transaction support.
I don't mean to suggest that Bitcoin can't adapt. Just that most of the advantages it has over physical / digital cash or credit disappears once you add such things. Once you have a bank or physical device governments will get into the game and start regulating with the express goal of eliminating anonymity for large transactions.
"... most of the advantages it has over physical / digital cash or credit disappears once you add such things. Once you have a ... physical device governments will get into the game and start regulating"
Not sure what you mean. By 'device' I didn't mean some special hardware developed by some special company, where the government can then regulate that industry. I just meant any computer. I'm saying that signing a transaction can be done offline on devices that are never connected to the Internet, such as an old laptop, or yes even a special device. There's no fundamental requirement to have the keys on your virus-ridden home PC at any time. This doesn't remove any of Bitcoin's advantages from what I can see.
And multi-signature transactions will allow for multi-factor authentication at a protocol level.
That's significantly worse from a user perspective than giving Amazon a credit card number to enable one click checkout or downloading a book from my kindle. It's true you could do anonymous transactions online, but while it's better than mailing people cash it's something of an edge case and I could also buy a Visa gift card and get the same sort of anonymity. Again, I like Bitcoin, but the problem IMO is how to make it both as convenient as a credit card and secure.
PS: Your also describing an adhock solution. As soon as you want to mass produce them to allow significant and convenient adoption you get into regulation issues. And by 'device' I am including just the software to manage your account from a cheap netbook.
