The "Cuban Five," which includes Ramon Labanino (top left), Gerardo Hernandez (top right), Fernando Gonzalez (bottom left), Antonio Guerrero (bottom right) and Rene Gonzalez (center), have become part of the new political intrigue in Cuba. (Alexandre Meneghini/Reuters)

Since their return to Havana last month after 16 years in U.S. federal prison, the remaining three members of the spy ring known as “the Cuban Five” have been a frequent presence on state television. Wherever they go — visiting universities or attending outdoor concerts in their honor — they are celebrated as “Heroes of the Republic.”

They speak with a confidence and a candor unusual among Communist officials of their generation, who rarely veer off-script or show emotion. Despite their years behind bars, the men are relatively young, at least by Cuban leadership standards.

And with each public appearance, more Cubans and Cuba-watchers wonder what role the five, and especially ringleader Gerardo Hernández, might play in the country’s political future.

Although several of them had not set foot on the island in 20 years, Havana’s ceaseless international campaign to free the men has arguably made them the most recognizable faces in the Cuban government after the Castros. A generation of Cuban schoolchildren has grown up memorizing their names and biographies.

Hernández, 49, was serving two life sentences plus 15 years when he was freed as part of a prisoner swap for a long-jailed CIA mole in Cuba that also triggered the release of Alan Gross, an American government subcontractor.

Where U.S.-Cuba relations stand and what may change

Sent by Havana to infiltrate anti-Castro groups in Miami, Hernández was convicted of conspiracy to commit murder, having passed along information that Cuba used in the 1996 downing of two civilian planes operated by the exile group Brothers to the Rescue, killing four.

“We dreamed about this moment for so long,” Hernández told Cuban television soon after his arrival, choking back tears. “The only thing that lifted our spirits was the thought of coming home, to be with the Cuban people again.”

“It was worth it,” he said.

The agents have said nothing specific about their plans. But when the Obama administration agreed to send them back, it possibly gave Cuba more than a group of intelligence operatives.

“We don’t know yet what they’ll do, but they return with tremendous prestige,” said Aurelio Alonso, a member of the small Havana civil society organization Cuba Posible, which advocates gradual reforms. “So far, they’ve demonstrated an extraordinary level of political maturity.”

Leadership succession remains a delicate subject on the island. Fidel Castro, 88 and retired, hasn’t been seen in public in a year. His brother Raúl, 83, says he will step down when his presidential term expires in 2018. Next in line is First Vice President Miguel Díaz-Canel, 54, a technocrat who has worked his way up through the ranks of the Communist Party but has yet to establish a political identity of his own.

Fidel Castro’s 47-year rule left as its legacy a political crisis that his brother’s presidency has only temporarily deferred. With power concentrated in a single figure for so long, it is unclear how any successor to the Castros will be able to command the authority needed to hold the one-party system together.

The Obama administration may have sent back more than a group of intelligence agents. (Stringer/Reuters)

Cuba is the only country in the Americas that does not allow its citizens to vote for their top leaders. In lieu of the ballot box, power in the Castro era has long derived from proximity to the brothers and acts of heroism and sacrifice in the service of their revolution. Some of the highest-level figures in the Communist Party and the Cuban government are septuagenarian generals who were once teenage soldiers in the Castros’ rebel army.

Raúl Castro has tried to change that. After taking charge when his older brother fell ill in 2006, he stunned Cubans by purging the ranks of younger civilian figures — among them the economy minister, Carlos Lage, and the foreign minister, Felipe Pérez Roque — who were close to his brother and were once viewed as possible successors. They were secretly recorded discussing their ambitions and coveting “the honey of power,” Fidel Castro said, “for which they had not sacrificed at all.”

As a transitional figure, Raúl Castro has endeavored to institutionalize political power in the Communist Party rather than in any single leader, in the style of the Chinese and Vietnamese models. He introduced term limits and promoted more women, Afro-Cubans and younger figures, making clear that power would go to those who worked their way up through the system and rose on their merits rather than on the strength of personal charisma.

The problem is that the island’s state-run media has spent half a century promoting the political legitimacy of the Castros by endlessly glorifying the daring feats of their guerrilla victory in 1959.

This culture of revolutionary heroism almost inevitably diminishes the younger figures in the government who have made their careers not on the battlefield — or in American prisons — but in the tedium of finance meetings and sugar-harvest planning sessions.

Such figures may face a crippling credibility deficit once the Castros are gone. No one knows what would happen if a civilian such as Díaz-Canel were to challenge any of the old, loyal comrades — who still dominate the party leadership and operate lucrative state-run companies in tourism, retail commerce and other sectors — after the Castros are no longer around to referee.

To date, only one of the Cuban Five, Fernando González, who returned last year after completing his prison term, has been placed in a civilian leadership role, as vice president of the Cuban Friendship Institute, which works with pro-Cuban groups abroad.

“I think they come to the Cuban political system with as much credibility as anybody,” said Arturo López-Levy, a former Cuban government analyst who is now a visiting scholar at New York University.

The agents’ revolutionary credentials are unassailable. As covert operatives in Miami, they were not a single unit but part of a larger intelligence-gathering network taken down by the FBI. The five are the only ones who refused to become FBI informants when faced with long prison terms.

“It’s very difficult to question someone who has made the kind of sacrifices for the revolution that they have,” López-Levy said.

Obama’s move to normalize relations almost ensures that Cuba’s post-Castro phase will be heavily defined by the island’s relationship with the United States and by a growing pressure on Cuba to open its political system and failed state-run economy. It is a scenario that does not bode well for a weak figure.

Cuban officials have watched Venezuela, where Nicolás Maduro, the handpicked heir to the late Hugo Chávez, struggles to make common-sense economic reforms, seemingly paralyzed by a fear that he will be accused of betraying the commander’s wishes. His approval rating has dropped to 22 percent, an all-time low.

Yet placing the five in future leadership roles might further antagonize anti-Castro groups in the United States. “If the Cuban government really wants amicable relations with Washington, I don’t think it would be wise for them to have anything to do with these folks,” said Frank Calzon, director the Washington-based Center for a Free Cuba, which opposes Obama’s thaw with Havana.

But in other ways, the men may be more prepared to engage with the United States than other Cuban officials of their generation.

They speak English. They have spent most of their adult lives in the United States. And despite the long imprisonment, they have displayed no resentment or animosity, repeatedly expressing gratitude to the American supporters and attorneys who took up their cause.

Calzon noted that notwithstanding the Cuban government’s frequent protests about the prison conditions, the agents returned home looking healthy and well-fed, unlike American captive Alan Gross, who returned frail and missing several teeth after five years in a Cuban military hospital.

As Hernández’s wife greeted him, Cubans were shocked to see that she was noticeably pregnant. Conjugal visits are not allowed in the U.S. federal prison system. But as part of the secret negotiations ahead of the prisoner swap, American officials allowed the couple to conceive by artificial insemination, or “remote control,” as Hernández joked on Cuban television.

Their daughter, Gema, was born Jan. 6, just 19 days after his return.