What do you think happens mortgage lending in such a scenario?
What percentage of current renters have a 20% downpayment ready for even something as large as a 50% drop in home values? In Toronto, last I checked it as 1.1m for the average house and about 800k for a reasonable condo. How many current renters do you honestly think have $110k/$80 ready for a downpayment?
A housing market collapse only benefits those with great sums of capital on the sidelines waiting to deploy.