I don't see how a debit card could work any other way, since VISA is a pull-based system. If I have Bitcoin on my own computer and I swipe the card, how does the right amount of BTC get sucked out of my computer and exchanged?
> Coinbase is insured against employee theft and hacking in an amount that exceeds the average value of online bitcoin it holds at any given time.
If someone steals 90% of Coinbase's transiently held coins, no insurance coverage.
Coinbase is a private company that is barely regulated. Any money put into Bitcoins should be money you are willing to lose.
Sorry dude but I can't down vote this hard enough. Please read about the history of Bitcoin exchanges, and for that matter the history of banks. They arent trustworthy, and become insolvent all the time. The FDIC exists for a reason.
Implementing interactive approval would be more difficult to integrate. Authorization systems typically respond pretty fast, so there might be automatic timeout in the payment chain (terminal, acquirer, schema network, issuer) if the transaction was waiting for your interactive confirmation. Maybe some magic with initial pre-auth and subsequent post-auth attempts at regular intervals could work but would be no fun to implement either.