[Idea] "Multicurrency Coin" System (Need Opinion)

I've had an idea to a (probably) revolutionary system
   The concept behind it is very simple.
   Lets imagine that Mr.WorldWet wants to buy a t-shirt in a store (online or physic store) but only has Bitcoin and the store only accepts Dollars.
   This is a problem that we face nowadays, and to solve that I propose the creation of a simple system that acts as a "Multicurrency Coin".
   The system is:
   Is an online service that acts as a bank with that "Multicurrency Coin". So, we deposit there our Bitcoins/Dogecoin/Litecoin/Dollars/Euro/etc..
   and the money is automatically converted into that "Multicurrency Coin". When we want to buy a product, we go to the Store (online or
   physic store) and we use a special credit card with that "Multicurrency Coin". So, in the moment of paying the system identifies the currency
   used by the store and converts automatically to that currency and makes the payment. If we want to withdraw the money, we go to a normal
   ATM and we make the withdraw using the local currency.

   Advantages:
   -> No need to exchange the money wherever we go or travel
   -> Less mess
   -> Easy to use
   -> Exchange Bitcoin/Litecoin/Dogecoin/Euro/Dollar/etc.. to other currency easily

   | Tell me what do u think about this idea bellow |
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