Okay so… somehow this episode, which should have come out in November, got missed. Thanks to eagle-eyed listener Tommy G who pointed this out. So consider this a bonus episode!
In his later years, Cosimo goes to war with Naples, gets saved by Joan of Arc (kind of) and René of Anjou and Charles VII. Then he joins a Holy League against the Turks and plays “pick the next Pope” a couple of times. Then, in his old age, he retires to his country estate to study philosophy, before finally dying in 1464, at the age of seventy-four.