Biden is so deep in mental decline that it can’t be hidden. Trump has said he won’t debate any Republican challengers because, basically, “Why should I?”
However, I predict that if the Democrats continue with this insanity of running again, it will be Trump who shows up to debate an empty chair. Unless the Dems are so stupid as to let Biden debate him.
Biden was up to debating Trump four years ago, but much has happened to him in the intervening years, and the word salads he often had have gotten noticeably more frequent and much worse, along with moments of sheer (“where am I? and what’s going on?”) confusion. He frequently wanders off and needs a guide to get him to where he’s going next.
What will it take to wake up the Dems that they need a younger candidate who looks more vigorous than Trump, not much much less.