I don't care about past performance, I'm only looking at the future and unless there will be a future building boom in the cities to increase supply(spoiler alert, it won't because a million reasons) and unless there will be a sharp drop in internal and external immigration to the cities with jobs, prices will keep rising.

Have you exhausted all options for why prices will only increase?

I can see a scenario in which inflation rises and increased mortgage rates deflate the current overvalued housing market.

It's already rising in the US, if the central bank figures out how to meet the 2% goal year over year it will raise the interest rates in a few years. Probably not before 2024 though.

Especially when the populational trends imply that demand for housing will go down on the distant future. Future performance is almost guaranteed to decouple from past performance at some point.

Your points are technically correct, the best kind of correct.

I'm not looking at any undetermined future point in time, if I'm ranting about housing prices it might be not unrealistic that I'd like to buy one in the next few years - and I've seen absolutely zero indication that the prices would suddenly drop by 20-40% to the point where I'd call them reasonable, like 15 years ago.

This chart should be far more prominent than it is in most discussions about housing in Germany:

https://www.interhyp.de/ratgeber/was-muss-ich-wissen/zinsen/...

The incredible increase in house prices tracks a dramatic decline in interest rates. Interest rates were at 1% last year, below inflation! I have no idea how interest rates will change in the next few years, but I do know they will not decline at the same rate as over the past 10 years. As soon as they go up, the prices will decline.

Huh?

Things will be different on the far future. The exact point when it will change is a matter of speculation, and all the warnings about timing the market apply. You implied a high certainty that nothing will change, ever, and talked about 15 years things.

There is a high likelihood that nothing will change in 5 years (even though COVID19 reduces those odds a lot, because a bunch of people just died). And there is very high likelihood that things will change a lot in 40 years. Time things at your own risk.