If 50-year mortgages become widely available, home prices in the US market will increase by approximately 10% to offset the lower monthly payments, negating any affordability benefits.
"If the 50-year mortgage option becomes a thing. Prices would adjust upward. So, yes, technically, if you look at a 50-year loan, the monthly payment is about 10% cheaper. But if you suddenly gave the entire US market a 10% discount, home prices would just go up by about the same amount, which means that longer mortgages don't solve affordability."