Jeb Bush just doesn’t have enough charisma to do well in a presidential race. Policies are important, but personality is more important in energizing voters. Dan Crenshaw, Don Jr. and many others have much more personal appeal. 2020 is not fully settled yet, but if Biden prevails, I think 2024 belongs to Trump if he wants it.
The 2024 nominee will be whomever Trump wants it to be.