This change will have zero practical effect. The economics of fourplexes and smaller multifamily units do not work. After purchasing the lot and tearing down or modifying an existing building, the costs are upwards of $750K per unit, well above the market value of the units. The only hope is that some of the new factory fabricated housing can reduce the costs to make these sorts of buildings feasible. Construction is the one industry where we've seen literally zero productive gains in the last 50 years, and that has become the limiting factor on affordability.