Maybe they reduce size and perhaps as well quality - though not quite sure about both. I'd prefer every time a house build in the 2020'ies over a house build in the 1970'ies (obviously in comparable location). Double glassing and wall/floor/roof insulation to mention only some obvious improvements in the last 50 years.
However - does not make any difference for the argument. Whatever it is - retirement villages will cream it from existing stock, and if they restart to build new, than either their customers will pay same for less or more for same.
Sounds like a good business proposal for the village no matter how you turn it.