Ah, the new Airport. The butt of many a joke for decades to come. I'll see your airport and raise you a lock, the dutch envisioned another channel in the North of the country (the 'dollardkanaal') and pre-emptively made a gigantic lock complex. Which they then had to demolish again because the channel was never dug. At least they managed to re-cycle the lock doors (these are now in the Nieuwenstatenzijl locks a few km to the East).
Fortunately Berlin already has three airports (but Tempelhof is closed) so for now the crisis is not imminent (and I think that is one of the reasons the new one is delayed, delaying it is not going to cause any disasters other than waste money, which is of course bad enough).
Just looking at the architecture of the airport compared with Charles de Gaulle, Oslo Airport and Shanghai Airport you can see that they all try to get a large surface for their terminals to make space for a lot of aircraft. The BER airport terminal buildings are built in a square, with little obvious room for expansion. I guess they could build in that square which looks like it has nothing in it, but a new and separate terminal building cluster is not optimal either. No, in combination with the fire gas thing it seems like this is the PHP of airports - bad design all around.
You can still see the scars in the land:
https://www.google.com/maps/place/Dollart/@53.3007551,7.0831...
Fortunately Berlin already has three airports (but Tempelhof is closed) so for now the crisis is not imminent (and I think that is one of the reasons the new one is delayed, delaying it is not going to cause any disasters other than waste money, which is of course bad enough).