Michelle, a nation turns its lonely eyes to you. Questions plague the party after Biden's painful debate. Unfortunately, given your determination never to run for public office, you are the only answer.
Biden, cannot, and should not, withdraw without a plausible alternative. Kamala is the logical choice, but her low poll numbers defy that logic. Other fine alternatives such as Whitmer, Shapiro, and Beshear, would alienate Black women, the most loyal foundation of the party. Also they are untested on the National stage, and not known beyond the cognoscenti.
You check all the boxes, and are most likely to box out Trump from rebounding to the White House. The threat to Democracy warrants the extreme sacrifice.
Choose a strong VP. Consider Beshear, but the choice is yours. Placate the bypassed Kamala with an offer of Secretary of State, and the promise to serve only one term.