In my reading of the Convention debates, as well as a book on the State ratifications, it is fair to say the fundamental difference between the federalists and anti-federalists was how long each thought the republic would endure before sliding into tyranny.
Without making any hard estimates in terms of years, the anti-federalists thought despotic government was just around the corner. The federalists thought it much further off.
I am convinced none would have thought we would last so long, for a republic can only reflect the values of its people.
I wonder what if anything would be thought of those who actively are working today to destroy the Constitution -claiming we have outlived out time as a sovereign State/empire?