It will not be a choice between Trump or Biden. The choice will be between Trump and Bidens VP candidate—supposedly a black female candidate — as it seems pretty clear that Biden is not mentally fit for the office. Thus the need to keep him hidden in his basement to prevent that from becoming so obvious.
Or, perhaps Biden will step aside at the last minute before the nomination for personal reasons and the convention will anoint a last minute Savior. Hillary? Cuomo?