I’m going to say Haley right now, but things could change.
DeSantis might be too damaged by his COVID response. His re-election campaign should indicate how viable he is.
Hawley might wait for 2028 or 2032, when his Senate seat is not up for grabs. If he runs for two offices at once (not sure if it’s allowed in MO) he’ll be open to a sneak attack from someone like Galloway.
Cruz and Crenshaw probably won’t run together. If Cruz runs again I think Crenshaw might want to take his place in the Senate, and Cruz himself might want him as his successor too.
Rick Scott is getting old, though a presidential ru could be an escape hatchet from a tough re-election campaign in the Senate,
Cotton maybe, but he’s too much of an ideologue to win.
Pence isn’t popular with the base. Even the evangelicals would probably gravitate towards someone like Cruz.
GOP is not nominating a woman of color in 4 years.
2024 nominee will be either Donald Trump himself (he could very well run again), Trump Jr, Tucker Carlson, or some other lunatic.