No - this is a terrible idea
This is a kick-the-can-down-the-road solution, and we've seen it before in Japan, and it was CRAZY.
In the 80s real estate prices in Tokyo were high, so they started offering 50-year mortgages to make things "more affordable..." if you stretch the loan, the monthly payment looks easier. But it's just extra leverage and we know what happens with leverage...
Prices went insane. At the peak, a single 0.44 square mile parcel in central Tokyo was valued more than all real estate in the entire state of California. The total land value of Japan exceeded that of the entire United States many-fold.
Then the bubble burst, and it was BRUTAL. Prices in Tokyo fell 60 to 80%. Tokyo real estate today is still > 50 percent cheaper than it was in 1989. Many buyers from that era never recovered their equity. Banks spent years holding bad loans, and the broader economy stagnated.
Longer mortgages did not make housing affordable. They made prices higher, slowed down equity accumulation, and left households more exposed when prices fell. The crash was deeper and the recovery was longer because everyone had borrowed too much.
For most people in the US, the house is the retirement plan. At retirement ~75% of the median Americans net worth is their primary residence. The 30 year mortgage aligns with people's lives - it pays down fast enough that they own their home by the time they stop working.
A 50 year mortgage changes that. Equity builds slowly. Leverage stays high. People remain exposed for longer. I like that we are thinking outside the box but this doesn't solve affordability, it hollows out the main wealth-building mechanism for the majority of the population and will have other bad implications IMO
The only solution is to build more! We need supply-side solutions not induced demand, c'mon.