During the housing bubble, getting a mortgage for a suburban home was much easier (not because houses were cheaper, but just because banks were more reckless in handing out mortgages). Nowadays, suburbs, even if socially more diverse, are more out of reach economically than they were, say 20 years ago. At the same time, we're at a point where the generation of 80s-90s tech entrepreneurs are hitting retirement age and, even if most probably aren't newly moving to the suburbs for the first time, that's one of the cadres that can afford to, and which might be looking to leave the city. So the educational/career background of suburbanites is also shifting.
I don't think this is quite true. The current housing crisis is a very recent phenomenon (at least outside of NYC/SF metros), especially for people who are willing to move to the suburbs. On a national average, housing prices are now 1.5X what they were at the beginning of COVID. In parts of the Sunbelt, its >2X. When you combine that with rising interest rates, your mortgage payment is >2X what it would have been in 2020 for the very same house.
However, the 2010's were a totally different story. If you kept your job after 2008, the early 2010's were literally the best buying opportunity for suburban single family homes since WWII! You had people with only modestly above average incomes becoming mega landlords during this period.
And while prices gradually increased in the late 2010's, they weren't obviously increasing faster than incomes. There was actually a slight nominal price decline after the initial efforts to raise interest rates in 2018-19. Suburban homes were more affordable than the historical average literally until the eve of COVID. Yes, underwriting standards were stricter, but if you could get a loan, mortgage rates were <= 5% for over a decade. IMO this is a hugely underrated factor in why so many voters keep counterintuitively saying the economy was better in 2020.
