Newsom and Hillary probably both think they have a chance. They could go for another governor--Whitmer or Shapiro (but they may be unwilling to nominate a Jew because that would cost them votes from some of their core constituencies). Maybe some other governor. But they may have to put a black person on the ticket for VP if they get rid of Kamala.
Stacey Abrams is still available, and AOC will be old enough to be elected by 2024.
Probably the Kerry - Edwards ticket in 2004, will be the last Democrat ticket ever with two heterosexual white men.
Given the Democrats desire to celebrate diversity and all of that, there must be diversity on the presidential ticket. It’s not optional.
So if Newsome gets the nod, his running mate must be a member of a grievance group. And if his running mate is a woman and a member of an ethnic or racial minority then they get to check off two boxes of the diversity scoreboard.