We have 1) inflation and 2) population growth. Given the limited amount of resources, land, and labor, why on earth would house prices remain steady?
You'd need at least one of these factors to be reversed, or demand for standalone housing to go down for cultural or economic reasons, before you see long term downward trends.
In general though I agree with the poster above that the affordability "crisis" is really an expectations crisis. Everyone wants to live in a nice neighborhood with great schools that is close to the top employers, but there's simply not enough space, so this results in high competition and therefore prices. For some reason nobody wants to move to the rust belt where houses are nice and cheap. People don't want houses, they want the BEST houses.