I still think there will be behind the scenes shenanigans at the convention to replace the cognizant-challenged Biden, and someone without a record (see Trump in 2016) carries less baggage in an election that is basically going to be decided by our nation's moderates.
I do agree that there is a good chance Biden will be replaced as the nominee before or during the Convention. I just don't see a route for Michelle Obama being accepted by acclamation. And more importantly, I don't believe she even wants the job, nor has there ever been any evidence of that. With Hillary, it was clear right from the start that she'd love the job herself with the "co-President" stuff. She
lives for this crap.
But Michelle Obama? The Presidency is incredibly confining, and a lot of work. I don't see anything suggesting she would be willing to make those kind of sacrifices, nor can I even think of why she'd want to give up the "retired Queen with no responsibilities and plenty of money and celebrity admirers" gig that she's had since they left office. From all accounts, she didn't really like being there the first time. Even if there was an arrangement where Barack would be the "real" President behind the scenes, that still only goes so far. She'd still have to do all the speeches, foreign trips, press conferences, etc..
Just because
we fear something doesn't mean the other side actually wants it to happen. I think that distinction has been overlooked.