It's possible. I can see a Bitcoin debit card (scan card, enter PIN, info is sent to the debit card companies' server, they send a transaction from your wallet) being possible, not sure about a Bitcoin credit card though.
Who's in charge of this mega corporation to be? Who handles chargebacks and overdraft fees? I see no solution unless new hardware is developed to support bitcoin transaction exclusively
Maybe something like this could work, but way more than cash than credit card:
You go with the bitcoins you want to spend in a paper, with public and private key.
You buy what you want, vendor charges all the bitcoins in your paper and gives you change in another paper you only have public key (or the private is just hidden).
That way you can spend bitcoins without a phone. But of course shop will need internet and laptop/tablet/smartphone to do it.
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Yes, that's also possible, but it would use a lot of paper.