More supply on limited land. Which will be bought out by the same 5 real estate companies, just like everything else.
https://twitter.com/cw4emeryville/status/1438862784024891394
Also, Berlin has a lot of land that could be built upon. Land is not a scarce resource in that particular corner of Europe.
Also, existing land use could see some improvements. Does it make sense to have a huge solar electricity park like this:
in the middle of a city with a shortage of housing? That is 150 x 500 m piece of land where at least 5 thousand people could live comfortably even without a need for high-rises. (6 story houses or so). In a walking distance from an existing U-bahn station.
(Not to mention the other factories around.)
There is a discussion in Prague about moving some big shopping centers from the wider center to the outskirts and using the freed land for construction. But everything takes long in our state of bureaucracy.