By Paul Reynolds
World affairs correspondent BBC News website
Raul Castro is expected to take over
Cuba is entering a danger zone faced by many societies where elderly leaders set in their ways seek to hand over an unchanged system to someone who shares their beliefs.
The Soviet Union collapsed partly because a series of dying men passed power from one to another.
One of the reasons for China's success is that it is determined not to saddle itself with such people. It is already moving younger men up the chain of command.
Yet in Cuba, Fidel Castro, while excluding himself from the top positions, will hang on, in his words, as "a soldier of ideas".
He intends to keep on offering his "reflections", while promising to be "careful". The impact of these reflections, careful or otherwise, is bound to be huge.
It is unlikely that he will countenance much change and if his brother Raul, aged 76 and the army commander, is selected as president by the National Assembly on Sunday, the chance of reform in Cuba for the immediate future is very limited.
It is probably limited in any case.
There could be tinkering around the edges but the fundamental philosophy of the current Cuban leadership is still revolutionary. It has stood tall on that in the past. It will stand or fall on that in the future.
The problem with liberalisation for such a government is that reform does not satisfy demand. It feeds it.
For the rest of the world, this means that the decisive days in Cuba are probably some way off.
Certainly the United States thinks so. A state department spokesman dismissed Raul Castro as "Castro lite".
Deputy Secretary of State John Negroponte (an old foe of Cuba who helped suppress the revolutions in central America) said the US embargo on Cuba would not end "anytime soon".
President Bush called for a "transition" to democracy, but without much expectation that it would happen.
The mood among Cuban exiles in Florida appeared muted.
One of their favourite blogs, Babalu, called for change (echoing the theme of the Democratic presidential candidates) but, again, more in hope than expectation.
"The one word that Cubans dream of is "cambio" which means change. Unlike the US where "change" is a trite slogan used by a politician's wife who isn't proud of our country, in Cuba change is a rallying cry," it said.
There could be some change if Barack Obama becomes president. From time to time over the Castro years, there has been a thaw in Cuban-American relations. There was one for a time under President Jimmy Carter.
There could be another under a President Obama. For a start, the restrictions on Americans travelling to Cuba could be eased. But that is not the kind of change that will change very much.
In Europe, attitudes towards Cuba are not as hard as they are in the US. (In Britain, the sale of buses to Cuba - much against American wishes - is still remembered).
A statement from Foreign Secretary David Miliband reflected a European recognition that good work on health and welfare has been done in Cuba, while calling for that elusive change.
"The Cuban people will now be looking to the future, a future which we hope will offer them political progress founded on democracy and human rights, and continued progress based on social justice and individual need. Like the rest of the EU, the UK is looking forward to productive relations which will bring benefits to both of our nations."