Beshear. Not strong enough to be risked on a substitute campaign, good record, complementary to her experience. Harris-Shapiro is probably a stronger ticket, but Shapiro's probably better off being saved for 2028/2032. Roy Cooper also a good choice for same reasons.
A 2-point bump in NC isn't worth making a conservative southern governor the presumptive Dem nominee in 2032! And a going from losing KY by 26 to losing it by 20 is *definitely* not worth it
Too old: Clinton 2016 (68 y/o), Biden 2020, 2024 (77, 81 y/o),
No mention of age in the press: Trump 2016,2020,2024(70, 74, 78 y/o), Bernie 2016, 2020 (74, 78 y/o)
If Biden drops out, I think anyone 70 or up is going to get Biden comparisons for the foreseeable future. I would guess that any candidate who can overcome that is a strong candidate on the merits.
In terms of how old they are now? I'd guess more like 60. Something like 1964-65 is my cutoff. So Pritzker would have one last shot, maybe, but if he can't swing in 2028 that's probably all she wrote. But the Beshear/Wes Moore young Xers feel like a demographic sweet spot. Shapiro too, at a stretch.