Fidel's brother, Raoul (not exactly a youngster, himself), is the "next in command." Sadly, Raoul is a real hard-liner; he almost makes Fidel seem like a "harmless, lovable fuzzball" by comparison (to borrow Rush's phrase).
Still, if Fidel has at last met his reward (one uses the term very loosely here), I will certainly shed no tears--to put it mildly. But realistically, I have no reason to think it will translate into a better future for the unfortunates who inhabit this failed Marxist state.
Has there ever been a successful marxist state?