I think that whatever the Democrats do should be guided by polling and focus groups, and not by what DC pundits and the chronically online have to say. If you base your political ideology and principles on polling and focus groups, shame on you. but if we're just narrowly talking about winning the next election, see what less engaged, ideologically non committed voters have to say.
That said, my gut tells me that the Dems best three choices, in order are
1.) Stay with Biden
2.) Have Kamala Harris run as an incumbent
3.) Have a mini, nation wide second primary and let the delegates hash things out and pick someone who did run in the primary in 2020.
I've already made the case for Biden and for option 3. So let me make a case for Kamala Harris.
1.) She ends this age question for good. She could shift the conversation from herself to what Trump said and is saying. The mainstream press will never facilitate a truly substantative conversation but it will start asking questions about Trump's cognitive decline. Ideology aside, someone saying totally unmoored to reality stuff, clearly and confidently, are usually crazier than people who speak general truths while tripping up on certain details.
2.) Kamala has not been a spectacular VP, lets not sugarcoat that. But she's brilliant (according to most lawyers I know, UC Berkeley's law school is far more meritocratic than any Ivy League school of law) and brilliant people often times become sloppy, undisciplined, and prone to bad habits when they aren't being challenged and the VP office is generally pretty unchallenging for any non George W headed administration. I think she'd respond well to pressure.
3.) Her law enforcement background is an overall asset. Us leftists will probably forever call her "Copmala," but that's because we have our doubts about anyone who has played any role in enforcing hierarchy, be they cops, prosecutors, hall monitors, or HOA officials, etc.. But overall, her experience as prosecutor will likely assuage some center leaning voters and her ability to make a case against Trump's agenda could be very useful and could open the eyes of a lot of normie voters.
4.) Speaking of the left, she's a Democrat so she'll get at least 70% of our vote. There's some on the left who will never vote for the Democratic Party. But there's still a small but geographically significant set of left swing voters out there. Their choice is Dems vs. 3rd party, stay home, and leaving presidential slot blank. I think that Kamala can win many of them over. If she were president, we would have, at the very minimum, the most knowledgeable President about Marxism in US history.
Biden probably thinks that socialism=Everyone gets paid the same, even brain surgeons. Trump probably thinks it means='when no food, lol."
Kamala was raised by Marxist, academic parents. even her goofy *** coconut tree remarks where about Historical Materialism. If I got to talk with her privately, we'd probably agree on the great questions of economics, class, and the extent to which class and caste conflicts drive History. She has been on the inside, she's seen how the system works, and she knows that the best one can do, from with in the system, is to restrain it and fundamental change will be won in the field by organizers. That is, ironically, the most leftists and Marxist of all takes on US politics. So she could throw us a few cultural bones and she's get like 85% of our vote.
(Just to be charitable to her haters, I'm not even going to mention the fact that she's to Biden's left on Palestine)
5.) Identity politics aren't the only thing; in fact, in electoral politics they only move the needle a little bit. But that little bit could decide things. People are looking at her and saying that Hillary was a women and she lost. But Hillary, despite carrying a lot of bad luck and baggage from Bill's neoliberalism, still won the popular vote by a lot in 2016. She lost in the EC and one might say that the same could happen to Kamala. But...
...I'd push back by saying that A.) Kamala has a clean slate compared to Clinton B.) Kamala could get those addition 100k votes in Michigan, Wisconsin, and Pennsylvania which lost Hillary Clinton the 2016 Election. In 2017, I was looking at the numbers and all of her bad luck aside, Hillary Clinton essentially lost the election in urban precincts in and around Detroit, Milwaukee, and Philadelphia. Harris' mere presence as a Black person in the race could change the make up the electorate enough to squeeze enough additional votes out of those places where Obama romped. She only has to partially recreate that energy and she's POTUS.
Of course, it's all risky and it looks like Biden will stay in it and I think he'll win but Dems should take a rare sigh of relief knowing that they have a strong substitute on deck.