Commercial buildings have had loading docks and freight elevators since long before the ADA. There wouldn't be a law
prohibiting ramps or curb cuts in any place where the value exceeds the cost. But then it would be engineers and competitive pressure doing the math instead of lawyers and politicians.
> permanent changes to the built world
None of that is permanent. Most buildings never make it to 100 years. The real estate consumed is a continuous cost. There is also a massive, ongoing cost to making new construction more expensive, because it increases housing scarcity and transfers wealth to landlords.
> benefit many and survive whatever byzantine rules might come in place to receiving high-tech wheelchairs from insurance or otherwise.
It seems extremely unlikely that in any non-apocalyptic future the technology will cease to be available in the market regardless of how dysfunctional insurance is. The least convenient plausible scenario is that you have to pay money for it. And the entire point is that on net this will be less money than people are having to pay for what's happening now, in the form of high rents.