I made a slight error in my post about Michael letting Fredo be a personal driver - they both did, but you figured it out either way Evita. Fredo started out driving his father around, years later on still driving people around picking people up from the airport under his kid brother.

No Vito and Michael wouldn't have anticipated that Fredo one day were to have Michael set up to be killed, but certainly should have realized that Freddy would grow recentful, whether or not it would have a significance to the future of the family.
But yes Lana, that Donship probably was the only trophy that would have sufficed to Fredo.