How do you figure? Germany, like any other developed country, can simply go to the delta: merchants who want to stay in business. Want your business license? Better comply with currency laws.
Bitcoin is too useful to be squashed by mere government regulation. If a few more countries employ these draconian measures, some cash-starved government will welcome Bitcoin in the future.
If regulators ("the body of Leviathan and the head of a social worker", to lift from Joseph Stromberg) were smart, they'd advocate easy exchange rules and impose a small tax on each transaction on the exchange.
Over the course of generations, I tend to have more faith in markets than in governments. That's why I think regulators will fail in their efforts in the long run.
So the state has a lot of tools.
That really annoys regulatory mindsets.
Bafin does not seem to care if you use btc to trade with your friends, but once € are involved they make the rules. Don't know if that angers you, but I think they have a case.
Both account keeping and converting one currency into another are well understood problems for regulators.