On gentrification

 Gentrification exists anywhere where it becomes viable for one household to buy out and combine two units. It's a normal process of urban regeneration. But it's hugely controversial because we've supressed the other half of the cycle--the conversion of depreciated single family residential into multi-family.

Millenial Housing Problems

"It leaves my friends and I, .... with gloomy prospects for how and where we can live. More people are being pushed out to the car-dependent suburbs because it's more affordable."

Millenial housing problems in a nutshell. Priced out of desired urban areas, exiled to suburbia, until you can make enough money to buy one of the few, rare, homes available in the urban areas. (And then you can get accused of gentrification! All because the local city counselor grew up in a 1950's suburb, and can't imagine anyone ever wanting to lie any other way, and so won't permit anything else to be built. Never mind that land values have tripled, and so to maintain the same level of affordability, densities need to triple as well. 

Gentrification / NextCity

Reading this at NextCity

For the sake of argument, let us define gentrification as the replacement of low-income households by higher income households. (Race being associated with income, it is also associated with racial shift). Low income households are almost universally renters. Renters move far more often than owners. Hence, as an area becomes more desirable (for whatever reason) low income renter are replaced by higher income renters. Low income is also associated with youth--incomes tend to rise over time. So as the incomes of low income renters rise, they start buying houses, in the neighborhoods in which they rent. Homeowners typically outbid investors for houses, so owner occupied housing tends to rise. This further displaces renters, as new owners tend to buy the cheapest houses (which are the most run-down, and thus have the cheapest rents). Over time, the existing stock of depredicated (older, run down) housing available for purchase is exhausted. Only nicer, newer, more expensive houses are available for rent--at higher rental costs. The 'climax ecosystem' consists of expensive homes (either owned or rented). The only thing that prevents this dynamic (keeps rents/cost low) is the production of new housing. Initially, it serves to blunt the demand for expensive housing (rented and owned), and reduce the conversion of depreciated properties (for rent or purchase) to restored/new properties.