I have, with a xapo card to purchase groceries for myself one time when I had no cash on myself. I just like how it is easier to manage and keep track of your money as transactions that happen would be displayed on the accompanying app on my android phone almost instantly.
Yes, Bitcoin debit cards and even Bitpay should just be a short-term solution until Bitcoin ecosystem doesn't grow enough so you can pay directly with your coins everywhere you want and need to.
I do agree that these are handy aids until this moment this doesn't happen, since this will take a while.
Merchants live on FIAT, unless FIAT goes away, which is very unlikely, i doubt we will ever be able to take FIAT out of the equation. Payments processor that will pay merchants in the currency they want will always be used, forever, until we get one global currency, which sound rather impossible because of sovereignty.
This isint specific to BTC, this is for all merchants.
I didn't want to say that Fiat needs to dissappear. It can stay just right there but with the Bitcoin on its side. For me, the complete adoption will be reached when we will almost everywhere have an option to check out and pay by using Bitcoin and other traditional financial payment systems like credit cards and money wallets!