Assuming we have conniving former-candidates maneuvering in the wings waiting for Trump to be disqualified, Ron DeSantis has a much wiser strategy. Supporting Trump by fundraising and issuing a condemnation of the "trial", he has positioned himself to be the default guy to rally the party to get even for denying Trump the opportunity to run. By already calling the proceedings a "kangaroo court". he can rage against lawfare and rally the troops.
On the other hand, Haley would not be smart to assert that a "convicted criminal" cannot head the Republican ticket. She needs some other prominent party members to make that statement or she'll come off as totally opportunistic and not principled at all. Besides, no one other than the GOPe wing of the party likes her.
By their initial positioning, DeSantis could be seen as the rightful successor while Haley will be seen as usurper. If Trump remains on the ballot, as is likely, DeSantis has positioned himself better for 2028.
DeSantis I could accept, Haley Never!
Nope, sorry... At this point it’s Trump or no one, not even DeSantis; who may be doing/saying the right things now, but maybe he’s just cagier than Nikki — after all, will that 10 Million be available to him once Trump is disqualified or imprisoned (or killed) and/or some Exec Order is signed declaring him ineligible?