Interest will shoot up, and people will get stuck with too much debt on floating rate loans. If a glut of housing hits the markets nationaly, it will drive prices down. If something else happens in the economy, job losses etc. That will force more salws and keep driving them down. Banks compesate for losses by jacking up rates.
Anyone who has a timeframe of longer than three years has heard this stuff before, many times. Even during general prosperity you'll have markets that tank.
In level markets no one has any business buying zero down. On wild markets no one has any business waiting one minute longer than necessary to get into the market.
In markets with 25% appreciation per year, watch out!
Do you see how this is different than what he says?