I have to, respectfully, disagree. Incumbency is strong, worth 2-3 points in the general election and there is no mechanism for replacing a presidential candidate at the head of the ticket. Biden has done an excellent job so far and it would be a weird self-own for dems to reject all of that or buy into Republican talking points and try to replace him. Also, a year out these numbers are soft soft soft. If the choice a year from now is convicted felon Trump vs anyone, the anyone will win, even more so if the anyone is a sitting president, even more more so if trump is running as a third party.