FIDEL CASTRO once famously acknowledged that his revolution required an "enemy," an "antithesis," a "counterrevolution" in order to develop. For nearly half a century, Cuban Americans have also largely defined themselves, socially and politically, in opposition to their enemy, Castro's regime.

Preferring to see themselves as exiles rather than as immigrants, Cubans in the United States cling to a powerful exodus story -- full of loss, longing and redemptive possibilities -- that has given meaning to their hardships and inspired their impressive climb up the American social ladder. Last week, news of Castro's incapacity sparked speculation about what a post-Fidel Cuba would look like. But there's another pressing question: What will become of Cuban Americans if and when the island opens up?

All cultural groups like to think of themselves as unique, but Cubans, and especially Cuban Americans, have a grand sense of exceptionalism. Their genesis tale in the United States is about exile, not immigration -- the "ideology," according to Lisandro Perez, sociologist at Florida International University, that "they were ... driven out, impelled to leave by a government and by a political system."

This sense of uniqueness -- combined with hatred for Castro and the fact that Cuba is an acknowledged U.S. enemy -- has enabled Cuban Americans, who make up one half of 1% of the U.S. population, to play an outsized and pivotal role in American politics and foreign policy.

One only need consider the Cuban Refugee Adjustment Act of 1966. Until the law was amended in 1996, all Cuban migrants, no matter their documentation, were allowed to apply for permanent resident status after one year in the U.S. Since 1996, the "wet feet/dry feet" policy has prevailed: Undocumented migrants caught off the coast of Florida are sent back to Cuba; those who make it to U.S. soil are still generally allowed to stay. Once admitted, they become eligible for federal refugee benefits.

Exceptionalism is strongest among the first generation of refugees who arrived after the revolution in 1959. They fought fiercely to remain culturally Cuban and made their longing to return to a liberated Cuba their calling card. They established a network of institutions to preserve their customs and traditions and to influence U.S. policy toward their homeland. They gravitated toward the Republican Party largely because of the GOP's tougher stance toward Castro.

Although U.S.-born Cuban Americans are not as politically focused on Cuba, the strident anti-Castro politics of the exile generation nonetheless defines the entire population to the rest of the United States. Though most U.S.-born Cuban Americans have never visited the island, many have inherited a romantic vision of the homeland from their parents and grandparents. After 50 years, the captive state of the mother country still serves as the organizing principle of Cuban American identity.

AND YET, at some level, Cuban Americans also understand that their exile state is a fiction. A 2004 survey of residents of Miami-Dade and Broward counties, Fla., where three in five ethnic Cubans in the U.S. reside, reveals that the majority do not consider it very likely that they will return to live on the island if it becomes a democracy. If and when the island opens up, Cuban Americans may finally have to acknowledge that they are in the U.S. by choice and begin to see themselves more as a traditional immigrant group. "Exile identity is always in opposition to something," says Cornell historian Maria Cristina Garcia, "but if the source of our opposition evaporates, then we'll have to rethink our identity as Cubans in the United States."

That doesn't mean that some Cuban Americans would not forge close ties to a post-communist Cuba. Businesspeople in particular would be well poised to help integrate a newly capitalist Cuba into the global economy. A post-communist island would also likely draw large numbers of visitors. But contact with their "homeland" may just cement the differences between the "two Cubas."

"Some [Cuban Americans] will visit and feel very Cuban," says Uva de Aragon, associate director of the Cuban Research Institute at Florida International University, "while others will realize how American they are."

The advent of a new democratic era also would probably spell the end of Cubans' privileged immigration status. That would result in declining numbers of newcomers, which would in turn deprive Cuban culture in the U.S. of the reinforcement it has long received from refugee arrivals.

And with the issue of communism off the table, Cuban American political organizations would be instantly deprived of their raison d'etre, and Cuban American voters could lose their special influence in U.S. politics. Described by some as Democrats with a Republican foreign policy, an increasingly diffuse Cuban American electorate could potentially gravitate away from the GOP.

None of this, however, necessarily spells an end to Cuban Americans' historical sense of uniqueness. "Being Cuban is a like an illness," says De Aragon, "a virus that is both hereditary and contagious. That island will continue to occupy our imaginations."