The Democrats aren't going to let Biden run if they don't think he can win. If it gets so bad that they don't think they have anything to lose, they'll go with Harris or Obama who will make abortion the number one issue, with the help of the media and our TV subscriptions. In this depraved excuse for a nation, that might be enough.
They'll have to threaten the 25th Amendment to get Biden to back down. Then try their luck with Kamala Harris.