Germans are a lot less likely to move aroubd than Americans so. Once you bought a house, chances are you still living there when you retire. So market value is a lot less important than the amount you pay every month for said housing once you retired.

This whole speculating on real estate value is more of an US thing than it is European. Outside of real estate investors, but those are the landlorda Germans, and others, rent from.

38% of US houses have no mortgage as all. And one assumes that enough people who have a mortgage are on track to pay it off eventually.

Many people do cash-out-refinances which ensures you never pay the house off, but if you just treat like the mortgage like rent and do nothing else (though if you can get a better interest rate refinancing for what you owe is often a good idea) you will pay it off. If you can afford the initial payment, your effective payment typically goes down over time as inflation brings the rest of your income up. Once you have the house half paid for odds are your payment is so low compared the income that you will have no problem paying the rest off. The early years are tough though before inflation works for you.

Of course if you do the cash-out refinance your payment raises more or less with inflation (just like rent) plus you get a nice chuck on cash to do whatever with. If you invest that cash wisely it might even be abetter investment than paying off the house (I don't think anyone has ever done this, but it is an option)