Biden might get a slight bump in those states, because he is popular with older African-Americans and their community leaders (e,g, preachers, deacons, church ladies, local party machine functionaries).
Overall, though, the age demographics are working against him. Younger voters don’t want a candidate who keeps looking to the past and/or who talks about restoring the unsustainable neoliberal-lite normal*, but someone who’s talking about the changes that are needed going forward. Wall Street Pete is too young to indulge in Biden’s empty nostalgia, but when it comes down to policy young people will take a septuagenarian calling for single-payer universal over a McKinsey alum in his 30s who wants them to keep dealing with for-profit health insurance.
[* I’d argue that the empty nostalgia is more of a visceral turn-off for young voters than the Third Way policy; it’s one of the reasons that Corbyn did poorly in the UK election. Both, however, are the kiss of death]
Well, as a university professor I’m technically in the petite bourgeoisie, so naturally suspect. Critics from Reich to Kierkegaard to Habermas have identified this class as the bulwark of fascism. However, members of the academic subclass have been in solidarity with workers from the time of Marx, and so most of the people I rub shoulders with in the 55+ age cohort have been pretty consistently progressive, even though yes, we’ve done OK in the system as it is. And many of my friends tell “kids about the 60s” as part of their job description, I don’t see that as a problem as long as they are telling the truth and retaining context.
I don’t think Sanders’ chronological age matters much to them. Young people really like him, not only because of his progressive policies but also because he isn’t the kind of septuagenarian who constantly feels he has to brag about and rely on things he did 50+ years ago to prove he’s a progressive. As I’ve said before, he’s the crabby old grampa who tells them the truth about how screwed they are by the system where their parents (who’ve done well under the system) won’t.
It will be great when a young progressive like Ocasio-Cortez is old enough to meet the requirements to hold the presidency, but this time around the only [serious] candidate under 40 is Buttigieg, who’s been an ambitious 45-year-old since high school.