This is all very nice, but I would like to see if things could get better between Cuba and the US in some alternate history. Nailing Fidel seems to be one possible way. Any comments?
It depends also on the leadership in Washington and the time period. Certain Presidents are not going to normalize relations with Cuba no matter what, unless the Party falls from power-which might be possible early on, if Che is killed or screws thing up upon assuming power. Later on, if Fidel goes, Raul will take power, and the party structure will have had time to crystallize-they will survive.
A run down of the various Presidents and their attitudes: Kennedy, Nixon, and Reagan all REALLY didn't like the Communist Party of Cuba, and Fidel Castro and Company hate Kennedy with all their hearts. I need not explain why. JFK wouldn't do it even if he wanted to in the aftermath of the Cuban Missile Crisis and pre-Vietnam. Politically impossible. Castro's personal hatred for Nixon was near pathological levels(he didn't like how Nixon was the one American he couldn't charm, convince, or fool in person when he went to the States in 1959), and vice versa-it was the international equivalent of Bobby and Lyndon, both parties could not think rationally about each other. So Nixon in Havana a la Beijing/Moscow/Cairo/Damascus is ASB. Reagan's Central American/Angolan policy against Castro's attempts to get involved and support among the Cubans in Florida is all need to say in regard to him. So with these three, it's the Party goes, or no improvement in relations.
LBJ would be unlikely with a surviving Castro due to the time period as well as well as his involvement in the Kennedy administration, even though Fidel didn't hate him and was open to negotiating with him, unlike Kennedy. Ford can't do anything substantial on foreign policy, and needs to watch Florida during the GOP meltdown. Carter was open to warming relations-by the time he is in power, if Fidel was to up and die, Raul would take over smoothly, and the Angolan adventure might not happen. Carter also has Nicaragua to his "credit", giving him credence in Castro's eyes. It will have to take place in 1977-1978 if it happens, before Afghanistan and Iran force Carter to take a harder line in foreign policy. There is also Bush Sr. and Clinton-with no Fidel, they might be willing to do it. Bush Sr. has a powerful whip hand with Cuba's economic collapse in the early 90s, but he has to worry about his domestic political situation-he needs Florida against Clinton, and he knows it. If he wins a second term, he might be open to trying. The latter did normalize with Vietnam, but after 1996 when Cuba shoots down American planes, it's unlikely. He also needs to watch the votes and the right wing...
So, Carter and Bush Sr. I think have the best shots at doing it with a surviving Fidel Castro. Get rid of him, and it depends on what happens afterwards.