The electoral strength of the Trump base is their ability to identify with Trump, which makes the political component of open defiance a guaranteed loser. None of Trump's presumptive successors have his advanced age, imagery of an unregimented approach to self-care, comfortable ease with crude mannerisms or showmanship.
A USA where the economy is poor and the Gen X and older cohorts have returned to 2010 levels of apathy is one where Newsom, Walz, Kelly, Booker, Ocasio-Cortez etc openly directing anybody they have authority over to disregard all instructions of federal personnel up to indefinitely detaining federal personnel does not stop them from sweeping in 2028.