In my experience, I found pedestrian-oriented neighborhoods with a more diverse built environment -- those that offer a wide variety of housing types and price ranges in close proximity -- are more resilient to racial turnover, and more conductive to long-term stable racial integration.

I grew up in an urban neighborhood that experienced racial transition over 20-30 years - what an outsider might call "white flight". In reality, racism was only a very small factor in the neighborhood's change. The neighborhood had a monoculture of small bungalows on ~3,000 square foot lots, built in the 1920s. For decades, many couples bought their first homes in the area, and when they could afford it, moved up and out. Some lower middle class and middle class folks (like my parents) liked the area, liked their neighbors, and stayed on. There was always turnover.

In the early 1970s, middle class black families started to replace some of the white families that moved out. No bricks through windows. No blockbusting. No panic selling. They were welcomed, much as many urbanists would like to think differently. White families also continued to move in and out. In the late 1980s, though, things changed. The convergence of a recession that hit the city hard, and a die-off of elderly residents, resulted in increased housing vacancies -- and plunging real estate prices. The vacancies left behind were now filled with low-income black families, aided in part by mortgage programs and housing vouchers. Middle class white and black families began to pull up stakes and leave, and housing turnover accelerated. It wasn't so much white flight as middle class flight.

So, where does urban design and race come in? There were few opportunities to move up, but stay in the neighborhood. If someone wanted a bigger, nicer house, their only choice was to leave the neighborhood. If they wanted to downsize, their only choice was to leave the neighborhood. The monoculture in housing also fostered a monoculture in culture. Most long-time homeowners were either retired or "upper lower" middle class -- teachers, clerical workers, librarians, nurses, skilled tradespeople and laborers, entry level cops and firefighters, and so on. The neighborhood was multi-ethnic, but not multi-class. The newcomers had little in common with their long-established neighbors.

The neighborhood was "urban" when it came to density, but it wasn't really quality urbanism - there were no parks, few amenities - excepting a few enclaves, it was just block after block after block of 1920s-era bungalows on 35' wide lots. There was no compelling reason for anyone to stay, if they had the means to leave, except their social network, and for many it was being chipped away house by house.

I've visited many, many urban ghettos in the US, and the one thing most seem have in common - the housing stock seems identical. Look at Detroit. The city's neighborhoods are, for the most part, each dominated by a single type of housing. Areas of high-end housing tend to be be islands in a sea of smaller bungalows and Cape Cods - Indian Village, Palmer Park, Boston-Edison.

Compare it to Buffalo, where a larger percentage of neighborhoods have more "transects" in a ped shed than what's normally found in Detroit. The city really doesn't have any neighborhoods that are solidly wealthy, but no shortage of places where the middle class and old money 1% rub shoulders.

Neighborhoods that succumbed to racial turnover in Buffalo tend to be Detroit-like "bungalow belts" on the East Side -- in the path of outward racial migration, and with little housing variety. Solidly white ethnic neighborhoods also tend to be dominated by bungalows, two-flats, or worker's cottages. Neighborhoods that have become integrated, yet still highly desirable among white homebuyers, tend to be either "multi-transect" mixed use, and socioeconomically diverse, or generally middle- to upper-middle class, where price is the main barrier to culture clash and later turnover.

TL/DR: thoughtful urban design can prevent "ghettos", and promote socioeconomic diversity in a small area. Greater geographic equity brings greater social equity.