I think Biden is a trojan horse. He's called himself a "transition candidate" and there have been several pretty obvious slip ups.
Both of these "slips" happened on the same day in Mid Sept.
Then, three weeks later, Pelosi makes it clear this isn't for the current president, but she's making sure she reminds everyone of the 25th amendment.
They aren't even trying to hide it. They're telling us, and they think it's ok b/c Trump is so bad LITERALLY anyone else will do. They're going to have some sort of medical event, or perhaps the Hunter stuff will get legs (maybe showing Biden took direct payment), and Biden will "reluctantly" step down leaving us with the most far left radical candidate in the huge field of Democrats this cycle.
It's actually 3D chess if you think about it. It's an amazingly cunning way to take a wildly unpopular politician and put that person in the White House.