Here's what I would like to see:
A debit card that holds a balance in BTC, but is usable in USD. As soon as I swipe my card, the conversion is made at the current spot price, the vendor is paid in USD, and the BTC equivalent is deducted from my account.
That would be the ultimate solution however it requires a very high level integration with credit card processing network.
The CC networks have a lot of layers:
Network provider (VISA, MC, AMEX)
Issuing Bank (Bank Of America, HSBC, CapitalOne)
Independent Issuer (Green dot, Netspend, etc)
Cobranded or white label solution (limited by capabilities of the independent issuer)
When a merchant swipes your card the request goes to the merchant's bank who sends it though the proper network (card type) to the issuing card's bank. The request doesn't go any further down "the chain" than the issuing bank. The bank looks at the funds available, card status, etc and either approves or declines the authorization. So unless there is an issuing bank (and I do mean a bank, not a financial company like Paypal or Netspend but a bank) that is willing to hold bitcoins as collateral and approve tx, and then sell enough coins to cover the charge I don't think we will see a solution like that.
One more modest option would be a an "auto charge" system. It would require an issuer which allows a company to see your account balance. When it drops below a user set amount the company sells enough coins to replenish the account. Even that requires a higher level of integration than I think is possible at this stage but wouldn't require the issuing bank to be involved.