HAVANA — Havana. - Going beyond the unending but ultimately idle speculation about Cuba's immediate future is perhaps the most daunting task any visitor to the island faces. How long Fidel Castro will last is, understandably, the favorite topic of journalists and diplomats, bettors and oddsmakers, but this is not necessarily the only question, or even the most important one that the thirty-something revolution poses today.
Viewed from a historical, hemispherical perspective, Cuba's advancement under Mr. Castro is impressive, in education, health and the eradication of extreme poverty, in the people's sense of dignity and the relative social homogeneity that contrasts so vividly with the exclusion of broad sectors of the population throughout Latin America. The key question is whether these achievements will outlast socialism, the revolution and Mr. Castro.
The experiment begun January 1, 1959, is in its most serious economic, political and ideological crisis.
The economic crisis is the most obvious; it can be seen and felt in the streets and homes of Havana. It is a creature with many fathers. The first was the end of the Soviet subsidy, which was probably larger and more decisive than most people, including the Cubans themselves, suspected.
That was compounded by the Soviet Union's dramatic non-compliance with its post-subsidy commitments. In his opening speech at the Fourth Communist Party Congress last month, Mr. Castro announced that the Soviet Union had delivered only 38 percent of the goods it agreed to send by September 30.
With the exception of a few isolated, specialized sectors, such as biotechnology, tourism and citrus, the island's economy is suffering from a total breakdown. Work motivation, productivity and economic mechanisms collapsed as the revolutionary mystique faded over the years and market mechanisms were not chosen to replace them.
Lastly, but certainly not insignificantly, Cuba is sinking because of the maintenance and tightening of the U.S. embargo, the consequences of which have become much more severe with the loss of the Soviet lifeline.
The economic policy mapped out to deal with this debacle is, paradoxically, rather sensible. For the first time, Mr. Castro has a coherent economic program that would capitalize on Cuba's comparative advantages -- its natural beauty, fertility and weather, and the expertise of thousands of highly trained scientists, engineers, doctors and professionals born from the revolution -- and trade for the rest.
Agriculture, tourism, medicine and biotechnology, backed by foreign investment and redirected in trade with Latin America, should, in theory, give the island a better chance for economic survival and even prosperity than most of its neighbors. The problem is, of course, that such a reconversion takes years to bring to fruition, and Fidel Castro is very quickly running out of time.
He is out of time in another sense, too, in a world where socialism has fallen by the wayside, and where any form of confrontation or even disagreement with the United States is viewed as quixotic if not foolhardy.
Under these circumstances, it would be extremely difficult to ask the Cuban people to endure deprivation on a scale they have not suffered since the early 1960s, with virtually no relief in sight for the short term. The socialist, utopian ideological motivation is no longer there, and while nationalism and pride continue to nurture Cuban endurance, the island's sense of isolation is overpowering. The revolution has just about lost the struggle it was used to winning, the one for the minds and broken hearts of the Cuban people.
Which brings us to the most important of Cuba's three crises: the political one. Fidel Castro has couched the people's choice in terms highly favorable to himself: Fidel or Miami, meaning a return to the Cuba before Fidel. Many Cubans watching events in the rest of Latin America and in Eastern Europe believe that they have a great deal to lose if the regime falls, and in some respects, they are right.
Havana's rulers have built some strongly supportive constituencies by persuading select sectors that things could get worse. The not-so-subliminal message is that a Miami comeback could signify the end of their standing, standard of living and pride. As one journalist told me: ''I don't want to go back to sweeping floors.''
The middle class of well-trained professionals -- doctors, engineers, technicians -- is being persuaded in this fashion, along with the military, the elderly, some youth and, to a certain extent, blacks.
Pandering to these constituencies, along with the persistence of a sophisticated and effective police state, could save the regime. But that tactic could also squander much of the revolution's achievements if, driven to despair, these influential sectors end up doing as their Eastern European cousins did: throwing the proverbial baby out with the Caribbean bathwater.