Some stray Cuba thoughts from a Smart Beltway Guy (who’s thinking along the lines of Mario Loyola):

the events to date in Cuba strongly suggest that a fierce internal struggle is now going on and that Raul’s absence from the airwaves is ample evidence that he is definitely not in control and cannot muster even a temporary consensus.
Politics in dictatorships rely heavily on the nuances of public appearances to demonstrate who has power and who doesn’t, information that is crucial to provide direction for those who are part of the ruling system but not part of the inner circles of power. Dictatorships require a public face of unchallengeable unity and cannot withstand public displays of infighting. For that reason, the #1 priority for any would-be successor are fawning public appearances and blanket media coverage focused on him in order to demonstrate to all that he has emerged as the unchallenged center of power. It is all orchestrated, and none of it is “news.” If others share the stage, this means that the struggle is continuing but is stalemated and a public face of collective unity is necessary to prevent the regime from collapsing for lack of someone in control. But eventually there must be a Number 1.
Sometimes the struggle is over quickly – Gorbachev quickly solidified his preeminence after the death of the puppet Chernenko who was a nonentity used as a place-holder by the competing power brokers while they carried on their internal battle. After Gorbachev’s emergence, the media switched to all-Gorbachev all the time. Similarly, Hua Guo-feng (remember him? No one does) was Mao’s appointed heir, and his appearances and utterances blanketed the airwaves, newspapers, etc. But he was quickly shoved aside by Deng Xiaoping who managed to organize a stable coalition behind him and emerge triumphant in the inner circle, then quickly and publicly threw out and humiliated the Gang of Four, his principal opponents. Appearances in the media tracked closely the rise and fall of this power struggle.
By contrast, in North Korea, there was no clear successor to Kim Il-sung. The presumptive heir, Kim Jong-il, was rumored to be dead for years because he so rarely appeared in public after his father’s death, indicating that it took a very long for him to actually consolidate control. All public acts, including coverage by newspapers, etc. – have that enduring purpose. Now coverage of him dominates the NK media every day.
Sometimes there’s a stalemate, so a collective leadership emerges for a while as the struggle continues and all of the key players appear collectively in the media. After Lenin’s death, it took Stalin – who was far from the most powerful of the factional leaders (Trotsky was #!) – many years to consolidate his power as he eliminated his rivals one by one. Public appearances of the leaders gradually narrowed until there was only one left. Similarly, after his death, a group emerged publicly which was gradually whittled down as it took Khrushchev about 3 years to eliminate his rivals. Then the public focus was on him all the time.
So, in Havana, I don’t see any other explanation that links all of the facts to date other than that a behind-the-scenes power struggle is raging. 1) The original fake letter – after the fact, not before, so obviously cooked up in a hurry. A letter on the central subject fin a dictatorship – who is in control? – and from a charismatic leader used to preening on TV? It’s almost funny. How about a message on Castro’s blog site? Clearly, he himself would have made the announcement beforehand if so momentous a decision as a “temporary” transfer of power were intended. (I know of no other example where a dictator voluntarily surrendered power, even temporarily. The entire base of their rule is that they alone rule. They’re either indispensable or dispensable). 2) The subsequent phony statements attributed to Castro – again no direct confirmation – in an effort to repress the growing speculation. Anyone could – and almost certainly did – put them together. The speculation could be ended at once by having Castro on screen, even if not speaking, even if in bed. Tito ruled from his hospital bed without interruption and after he had had a leg amputated while he was in his 80s. Again, necessary for the preservation of power. No “temporary” transfer there. 3) Raul’s non-appearance in public, when the highest priority in transitions is to secure a prominent public appearance and be presented as the unanimous heir and thereby signal to all that the struggle is over. Given that Raul is obviously having trouble in achieving this crucial goal after so many days, it’s a strong indication that he is not in control, that other powerful contenders are active, that they are fiercely battling it out among themselves, and that they are so factionalized that they can’t agree even on having Raul or anyone else as a figurehead while they continue the struggle in the background. If a group photo ever emerges, that means there’s a stalemate. A blank means that even an interim solution can’t be arrived at.
This is not an original interpretation of what’s going on in Cuba, as this conclusion is a common one. It’s merely speculation extrapolating from similar situations in other dictatorships.