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?
Right, I just want to warn people away from putting significant Bitcoin holdings directly into Coinbase to use this card without being educated on the risks.
The risk of what? Coinbase stealing everyone users bitcoins and running away? Better not use any bank, credit union, or money transferring service to stay safe.
Banks, credit unions, and money transferring institutions are heavy regulated businesses that have to follow rules. Money you have in bank and credit union accounts are also insured.
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.
This is only insurance for their hot wallet (Quite literally, the cash that a bank would keep in their teller registers.) The overwhelming majority of their deposits are not insured.
How many traditional financial institutions have done an exit scam on their users, though? Exit scams happen all the time with Bitcoin exchanges and dark net markets.
Your issuer could talk directly to your private wallet (e.g. on your phone or on server). You could preapprove requests coming from your issuer to be automatically executed so that there is no payment delay. This scenario would be somewhat similar to Direct Debit transaction and would require wallet software supporting automated requests.
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.
The idea is to use it like a charge card and not like a depository for your bitcoins (since any bitcoins you put towards the system isn't yours anymore).