After his arrest for the Moncada Barracks attack of 1953, Fidel Castro was sentenced to 15 years in jail.
In a moment of confidence having won the Presidential election unopposed, and also seeking some respectability, Cuban dictator Fulgencio Batista released him and several other of Castro's fellow prisoners in May 1955. He fled to Mexico and then returned to Cuba to lead an ultimately successful guerrilla movement starting in 1956.
Although non-Castro Cubas are not something I have seen much of, and could make an interesting storyline in their own right, what I'm most interested would be the impact of a delayed Cuban revolution and how it might change the texture and events of the 1960s. Since Fidel died a short time ago and his bro is still alive, he's got plenty of time for comebacks if he does not roll the dice and win in the 1950s.
In other words, I'm more interested in looking at the consequences of a late Castro rather than a dead or forever-out-of-business Castro.
For instance, had Castro served his full prison term, he would have been released in 1968.
It's a bit mechanical, but lacking anything better, a timeline like OTLs, but just 13 years later might see Castro might see Castro starting a a guerrilla movement in 1969 or 1970, and taking power in 1973.
There would be some interesting Cold War divergences by that point if there is no Communist Cuba through the 1960s, but it pops up in 1973.
As an alternative, if you think it unrealistic for him not to be released until his full-term was served, than what if he were released after 7 years time served, 1960? I would think it is plausible that he could be released in some intermediate timeframe between OTL's outcome and the end of his sentence, if prisoner amnesties were a frequent or occasional occurence in Cuba, or political change in Cuba brought about the release of the Moncada attackers.
So, using the same method above, a Castro released in 1960, starts an insurgency in 1961 and takes power in 1964.
Even that has major effects on the events of the Kennedy administration.
This premise raises some other questions. If Castro were not released until 1960 or 1968, would Batista even still be in power when Fidel walks? Or would Batista have been overthrown or retired, exiled or bought out in the meantime?
It's hard to say, although I don't think any Cuban regime pre-Castro last more than a decade.
Could Castro have come to power via a legitimate political path, and either held on to it dictatorially, or yielded it peacefully via electoral politics? That could be interesting. Maybe his revolutionary youth could have been an advertisement for a later electoral campaign, like Hugo Chavez's coup was for him by the time he ultimately got elected.
Your thoughts on any of the above?
To resummarize, the multiple lines of thought above, they are:
a) Cuban revolution pretty similar to OTL 13 years later
b) Cuban revolution pretty similar to OTL just 5 years later
c) Castro's career if the Batista dicatorship were out of power for non-Castro reasons by the time Castro was released (indeed, Batista losing power, if it happens before 1968, could quite likely be the occasion for Castro getting released)