I think it's an excellent idea regarding the evolution of Bitcoin in general. You have the fastest and safest transaction. You do not need to bring anything with you if not the QR code that you can very well keep on your smartphone.
the idea actually not very clear, how about prices?
we all know that btc's prices fluctuating and sometimes spikes are great.. so does it mean that the prices for good will be fluctuating as well? right?
and other thing - the transaction cost is really huge.. so you will not be able to buy some milk with BTC )) cause cost of transaction will be much much more then the cost of milk..