> Germany's population has been on decline for ~30 years due to demographics
The thing is – within that time frame it hasn't, actually. There have been some years with slight decreases, but those have been balanced by other years with increases, and compared to 1990 population is actually definitively slightly up (83.2 millions last year vs. 79.8 millions). Combined with a decreasing average household size (2.27 in 1991 vs 1.99 in 2019) and internal migration those things by themselves will probably generate enough pressure on the housing markets in and around the prospering parts of the country, even without any added financial shenanigans on top.
The thing is – within that time frame it hasn't, actually. There have been some years with slight decreases, but those have been balanced by other years with increases, and compared to 1990 population is actually definitively slightly up (83.2 millions last year vs. 79.8 millions). Combined with a decreasing average household size (2.27 in 1991 vs 1.99 in 2019) and internal migration those things by themselves will probably generate enough pressure on the housing markets in and around the prospering parts of the country, even without any added financial shenanigans on top.