> how volatility and rapidly deflating currency would effect their cash flow.
Not at all? You obviously don't understand what a bitcoin debit card is. It's just like a normal debit card, but you fund it with bitcoin. The company you get the card from sells your bitcoin for fiat currency at the time you make a purchase (or at the time you top up the card, depending on how they do it).
The properties of bitcoin are completely irrelevant to the mechanics of the card.
Not at all? You obviously don't understand what a bitcoin debit card is. It's just like a normal debit card, but you fund it with bitcoin. The company you get the card from sells your bitcoin for fiat currency at the time you make a purchase (or at the time you top up the card, depending on how they do it).
The properties of bitcoin are completely irrelevant to the mechanics of the card.