This, and it is already happening in as we speak. London, Hong Kong, South Korea ( a little different but all the same ) Vancouver, Sydney. Basically anywhere you see housing bubble.
The trigger of re-evaluation also hurts banks's balance sheet. Crediting Rating agency, a whole lots of other financial institution. i.e Their interest is to not let it fall.
Banks? Banks don’t buy up houses, banks are what helps individuals buy houses. Again this just sounds like someone who recently watched the big short