I mean, 20k is… Not that much higher than many places now available on say green, so at that price those large flats would be pretty darn sustainable to rent, especially as you can then re-earn this rent, and unlike 100k, 20k instead of 8 or 12k for a flat is not that big of a difference in the work.
So this would just devalue them by a ton. Maybe something more like 50k, and one that cannot be earned through earning cap?