Obama-Castro: Has 'the fever' broken?

Republican Sen. Marco Rubio says it does "absolutely nothing to further human rights," and Democratic Sen. Robert Menedez says it "vindicated the brutal behavior of the Cuban government."

But President Barack Obama's move to normalize relations with Havana is raising the promise in South Florida that it will open up exchanges after generations of enmity.

Read MoreObama: We will end an outdated approach toward Cuba

Calle Ocho in Little Havana, Miami.
Peeter Viisimaa | Getty Images
Calle Ocho in Little Havana, Miami.

"For many it will create hope that there is a thawing, and economic development will lead to the democratization of Cuba," said Susan MacManus, a University of South Florida professor and an expert on Florida politics.

Marifeli Perez-Stable, a sociology professor at Florida International University, notes that the Cuban community in Florida is no longer the monolith it once was. In particular, the millennial generation of Cuban-Americans is more open to ending the more than half-century-old trade embargo under the right conditions.

Read MoreRubio: Congress won't support lifting embargo

"Public opinion has been changing," Perez-Stable said in a telephone interview. "This is such an old and entrenched topic that of course there's going to be charged, emotional reactions (among first- and second-generation immigrants). And those people are entitled to be upset. Since '09, when Cuban-Americans have been allowed to go to Cuba as often as they want and send as much money as they can, even people who are more conservative on U.S. policy on Cuba don't speak up on that as much anymore."

Why Cuba wants embargo lifted
Why Cuba wants embargo lifted   

From Cuba's viewpoint, she said, the move reflects the growing power of Raul Castro, who succeeded his ailing brother, Fidel, as president nearly a decade ago, against hard-liners who think improving relations with the United States is going to undermine socialism.

"I think this sends a signal that Raul, who has faced opposition from this same sector in terms of the economic reforms, may be gaining strength," she said. "Before Fidel could say 'no,' and everything is shut down, But Raul, when he dies, he wants to have Cuba in better shape than it was when he took over."

Read MoreViva cigars! Easing of Cuba trade would be 'huge'

MacManus said there's already been great hope among the emigre community in Florida of closer ties with their former homeland. But she noted a residual distrust among many.

"They are really ready to open up Cuba, but it's just the nagging presence of the Castros. But for the average person, more people think that opening it up is a good thing rather than a bad thing."

Added Perez-Stable: "I am elated, with the caveat, given that it's Cuba, anything can happen from either side. We've been here before, and something always happens and undermines this improvement. At some point the fever will break."

Franco Origlia | Getty Images