This is very interesting read. I am not trying to make any partisan points here but so much came to me as I read it. So here goes in no certain order.
Joe Manchin is the man. If the Demos are not going to be able to do election reform or add states with 0 Repub help unless he agrees to end the filibuster. Manchin is the most powerful senator in the country right now. If Shor is right then the Demos are in trouble for some time to come without those measures and they cannot get rid of Manchin, since he is in a red state, they just have to figure out a way to flip them. Good luck Demos.
I think Shor is right in that the white progressive elite is becoming the core of the Democratic party. And some of the policies they push will drive away some racial minorities. The right Repub candidate in 2024 can really take advantage of that split.
Along those lines I do think we are seeing a party realignment. It use to be that the Repubs were the party of the rich elite and Demos of the "common man." But with more of the highly educated and financially well off coming to the Demos they have become the party of the elite. And at least culturally the Repubs are becoming the party of the "common man."
I think Shor is wrong in that only Trump would have beaten Clinton. She was an exceptionally bad candidate. But the way a, say Rubio, would have beaten her would have been a different mix of states. Trump brought identity politics to the Repubs in a big way and I do not know if they can easily extract themselves from that. The Demos have to worry about the white elite/racial minority split but the Repubs will struggle with the MAGA/traditional Republican split for some time to come.