DeSantis could definitely win, and given early polling has shown him up in New Hampshire, it's not that hard to see 2008 parallels where Obama's surprise win in Iowa helped him to close the gap with Clinton. Trump also lost Iowa in 2016, so evidence already exists that Iowa Republicans could be open to something other than Trump's brand of conservatism.
Also primaries especially republican ones are all about momentum so if DeSantis can win NH/SC i think he’d actually be the favorite then and if he won 3 of the first 4 he’d be the nominee