Further clarification: There are three distinct questions here.
1. Does there exist some candidate who could do better than Biden if they were •already• the Dem nominee?
2. Would switching candidates midstream •now• help the situation? Even be logistically feasible?
3. Should we trust the forces that have pushed item 2 to the top of the news, even above the SCOTUS going full Trump-can-be-a-dictator?
The answers are:
1. Probably.
2. Highly unlikely.
3. Certainly not.