it's already done, many giant companies in china that make payment transactions using bitcon.
"only on a large scale", because transaction costs are high enough, bitcoins are not suitable for use as small payouts. for example to buy food, to salon and many more..
As far as I know, if a user uses Bitcoin as a payment method, then Germany will not tax it. This means that bitcoin is considered a legal payment method in Germany and enjoys the same status as a legal currency.