Donald Trump has no clue how govt works. He claims that he's "left instructions," in the event he's assassinated, and that it will involve "dire consequences" for Iran.
Govt doesn't work that way. It's not Trump's property that he can dispose of when he's dead. Any response to the assassination of a USG official would be the responsibility of the then president, not Donald Trump or his heirs. All that's before you get to who did what to whom, when and why.