I’m not confident about my reasoning at all. That’s why I’m offering here for critique.
For examples, one of the way to separate buyers is first-time buyers v.s. investors in housing market; or trader v.s. holder in stock market. As itsdd pointed out, sentiments change, and I think it affects investors more. As a group, they tend to buy high and sell low.
Current real-estate price has already made first-time buyer hard to qualify or even if they do, nerdwallet survey shows 1/3 of them feeling less financially secure after the purchase. That would probably mean that investors are the main buyers now. The trend is very pronounced in a bubble country such as China (https://qz.com/1615596/chinas-debt-disease-is-infecting-its-housing-market/) but I don’t know where to get the corresponding data in US.
That said, I just said that massive decline (i.e. reverting back to historical median) in short-term (2-3 years) in unlikely. One of the wild card that I watch for is China. Given its global influence today, a turmoil in its economy can have severe international consequences, especially considering internal politics alone has a potential to bring turmoil in China, rather than the external factors like trade war. Xi should worry more about Hong Kong than Trump.