This sounds like a veery great idea which will really come in as a good alternative for the banks but in this case have you considered the fees and the charges that may be attached to the use if these coins because I know for sure that sending any coins from one wallet to the other usually cost a fee and who's going to bear that fee will be one challenge this payment method will encounter, that alone can even get some customers not tor want to use it if they consider  the charge to be high that they can not spare for the volume of transactions they are carrying out at a time just like the daily spending kind of transactions which are in units and occurs frequently depending on the needs you are having to take care of in a day, it's still a good regardless.