its not out of the realm of possibilities that he gets assassinated by a trump supporter or a white supremacist (not that theres a difference between the two, right?) if he gets into office. then his VP will take over.
in ANY case, he wont be making any of the calls on things if he gets into office.
if anyone is familiar with FDRs last term in office, he was in absolutely terrible shape (while his doctor kept telling the press that he was in fantastic health). i think the doctors said he could only work for 4 hours a day. he went to a meeting or two and the rest of the time his communist cabinet and secretaries ran the country. this will be a repeat of history.