Lol. There is no time. Replacing an incumbent at the last minute is a death sentence for a political campaign. It would be the most foolish option. Even if Biden came out and said he’s stepping back and letting Kamala Harris take the spot, you’d be fighting an uphill battle for people who haven’t been paying attention to her work as VP, which the uninformed thinks does nothing.
That’s not even taking into account all the sexist and racist shitheads who have been doing all the fear mongering and hand-wringing about the prospect of Harris becoming president by simply being VP. We have a bunch of really shitty people in this country…