Hi @loveon,
Weiting from WageCan here.
Basically, those cards could convert cryptocurrencies into fiat currencies, e.g. USD, EUR, and GBP, and load to your cards.
And you could withdraw money from ATMs with those cards, just like how you do with your normal debit card.
But as far as I know, none of the cards mentioned above could convert Steem to fiat curriencies.
Hope this answer clears a bit of your question :)
This was very helpful. I've been trying to figure out if it was worth getting one of these to begin with.
It depends on the fees though. Some support ER20 tokens and other cryptos. TenX and Wirex looks cool. I prefer TenX for now. If you were to convert to Steem to Ethereum and then load your account from a cryptocurrency card provider which supports Eth and ECR20 tokens, it may just be worth it. ;-).