While falling mortgage rates will improve affordability, the "lock-in effect" for existing homeowners with ultra-low rates will persist. This will suppress the typical sales volume rebound, leading to an anemic 3% growth in purchase volumes, a historically tepid response to improved affordability conditions.
As mortgage rates fall, more homeowners will list their properties, increasing inventory. This rise in supply will happen concurrently with the rise in demand from improved affordability. This dynamic will prevent a surge in home prices, keeping annual appreciation capped at a modest 2% for the upcoming year.
While a 50-year mortgage could significantly lower monthly payments to aid affordability, it has a major drawback. The total interest paid over the life of the loan would likely be double that of a traditional 30-year mortgage. This prohibitive cost, along with technical challenges, would likely suppress borrower demand for such a product.
Proposals to allow homeowners to take their low-rate mortgages with them (portability) or transfer them to a buyer (assumability) cannot be retroactively applied due to contract law. Creating new mortgages with these features is possible, but the added benefits to the borrower would likely result in a higher, not lower, interest rate.