OTL, FDR's death is one of the saddest things ever.
He spent so much time and effort to achieve victory in the greatest war in history, toward building a new international covenant, and toward building an better and more free America. And yet, he never lived to see these things. And his own hated rival, Adolf, outlived him by 18 days.
ITTL, his death is that and Franz Ferdinand's: it had tragic consequences for humanity.
It kind of begs the question of whether or not Roosevelt replacing Wallace with Truman or some other firebrand would've seen the USA elect ol' Blood and Guts himself. On the other hand? No other president had the platinum-coated balls to go after the segregationists as Patton did.