This is from Four Brands of Impossible by Norman Kagan, a short story of science fiction copyright 1964 by Mercury Press, Inc.:
“…Did you know we have a top-secret Congressional Project to automate the presidency? Fact. The chairman of the Department of Cybernetics told me the system philosophy behind it: Roosevelt showed that someone could be President as long as he liked. Truman proved that anyone could be President. Eisenhower demonstrated that you don’t really need a President. And Kennedy was further proof that it’s dangerous to be a human President. So we’re working out a way to automate the office.”
Leaving aside the question of why those demonstrations lead to the conclusion that the office should be automated, if Mr. Kagan was writing today, I wonder how this would change. FDR still stands as the best evidence that someone could be President as long as he liked, though I suspect there are many who feel Reagan could have held the office as long as he wanted if not for the constitutional limit.
That anyone could be President might have been more recently shown by Reagan, Clinton, Bush, and Obama.
That we don’t really need a President by Ford perhaps, or maybe Reagan’s second term?
That it is dangerous to be President? Reagan is the only President to be shot since Kennedy.
So, really, if the paragraph was written today, Reagan could be used to fulfill all of the categories!!