Don’t underestimate the power of status quo. Also, how unpopular it is to criminalize things.
Also, Germany has coalition governments. As long as there is no CDU/CSU and AfD coalition (and then Germany would have worse problems than recreational marijuana) at least one of the currently governing parties will be part of the next coalition.
Given that together with how hard the status quo is to change I’m relatively optimistic. Even though the conservative highly irrational, science and fact denying course is deeply worrying. So they might be ready to govern with fascists. But then, as I said, recreational marijuana is not my most pressing worry.