[grumple]

Why do you think the neighborhoods will die without more housing? I've watched wealthy neighborhoods in my city continue relatively unchanged for multiple generations. Once you have a thriving neighborhood, you don't need to continue changing things just to squeeze more people into it. What ends up happening (and I see this in some other neighborhoods, like my own) is that the things that made the neighborhood desirable (restaurants, retail, parks, affordable single family homes) get squeezed out in order to make room for more housing. The rents for the commercial spaces increase beyond what they could possibly earn. Once this is completed, now you have a bunch of housing in an area nobody wants to live in. People leave, then the area becomes blighted and the density gets torn down to build single family homes with yards...

This happened in my neighborhood in the mid-20th century - a huge, thriving, dense neighborhood was abandoned and destroyed as the industry in the area slowly failed. Buildings were turned into suburban-style lots, and over the past 50 years gradually gentrified and those empty spaces turned into more, denser housing. We're currently somewhere between the "local amenities can't keep up with the population" stage and the "housing is replacing commerce" stage.