I definitely see this in Palo Alto! Even 15 years ago PA had a lower median income than most surrounding towns; cops and firefighters etc could grow up attending Paly (high school) and live in town. There was an aggressive effort to maintain Section 8 housing and a more mixed population.

But since the real estate interests took over the city counsel that has all collapsed. The SRO housing has been converted to expensive boutique hotels, and a greater "I've got mine jack" attitude has taken hold. There are few blue collar folks who can afford to live in town any more.