The overall population of Germany is not declining yet, in fact last year the German population has never been as high. In general, if Germany wants to keep its economy the population has to continue increasing until the boomers are dead. So yes, counter intuitively, for now there is going to be a major pressure on the housing market at least until the peak. Germany is a major immigration target inside the EU so it's not met with the same fate as poorer european economies like Russia, Ukraine, or Italy.

The high rents in places like Munich are due to the urban areas seeing a major boom: that's where the jobs are, that's where the immigrants are going, that's where the young people from the countryside are going.