You don't seem to have considered the technological issues in play. A debit card is a passive medium, and as such can only operate by giving full access to whoever reads it (and has the PIN); it essentially gives up its private key to whoever reads the stripe. Giving out your private key is so 20th century.

or what about a regular credit card, but u pay with Bitcoin over the internet (that could work)

Yes, I think we'll see this in the future. The payments will probably be off-chain and authorized by an online wallet service (holding limited funds), but it will allow people to spend their coins in a practical manner.

Good point. Coinkite is pushing functional debit card use right now.

A store can put a QR code on items in a store as a pricetag, and with the right web backend, you can use your smartphone to buy the stuff right there, not have to wait in line, and leave the store with a digital receipt on your browser screen.

Loss prevention agents can see the item locations in the store where you bought stuff, and visually correlate that with cart contents leaving the store with an overhead camera pointed and zoomed down to cart level. In most cases this will be done in a second with a good eye (or optical recognition of items), and any questions further than that will mean you just have to show your digital receipt on your screen.

By the time you get to the door, doublespend attempts will be detected, so merchants can feel safer accepting BTC as people shop, than having to deal with credit card fraud and paying cashiers to waste time trying to deter/prevent it.

That is a revolutionary step further than self-checkout, where you have to wait in line to use a central computer bank.

Are you kiddin us?