Market will resolve based on the first person to serve in a role for which Trump has announced his planned nominee. That is, if in 2024 Rubio announces he would prefer not to be Sec’y of State in order to spend more time with his beloved yaks, but he ends up as Sec’y of State in 2027, he would count for this. If he somehow ends up Sec’y of the Interior instead, that would also count. (As two, actually, since it would displace another announcee.)