What happens if a US presidential candidate dies? Joe Biden and Donald Trump are the two oldest candidates in US history. If either needs to be replaced, what next? from the Guardian

'....knowingly and willfully mailing or otherwise making "any threat to take the life of, to kidnap, or to inflict great bodily harm upon the president of the United States" is a federal crime in the USA'. (Wiki). Needless to say, please keep this discussion legal.