The reason the suburbs (especially in the sunbelt) are trending so fast is because of generational turnover so no
Considering how well Cox/Ducey/Abbott etc performed in the same "trending away" suburbs, it seems clear imo that the big change is political and not generational.
Or Mitt Romney in 2012, for that matter. The kinds of swings we saw in Orange County, CA or Mason County, WV can’t be explained generational turnover alone, unless you’re being deliberately obtuse.
I do think the ~35 y/o Millennial couples buying their single family home in the suburbs and having their 1-3 kids are markedly more liberal than Boomers were at the age when they did the same. That seems an underrated part of the story. The suburbs are now taking on these voters that turned many city centers from 65% to 85% Dem during 2004-12, and the center cities are if anything moving a bit to the right since ~2015. This shows up most in states with small counties.
I'd also add that the impetus behind the migration to suburban areas is much different than it was in the mid-to-late 20th century. In many American cities, the price of housing and other living expenses is increasing at a dramatic rate that many people are moving out of the central city to find more affordable options in other parts of the metro area (this is especially true for victims of gentrification). Many of these new suburban residents are not only more left-wing on social issues but also fiscal issues than previous generations of suburbanites.
