Whether Trump will actually stifle the opening, touted as one of President Barack Obama's signature foreign policy achievements, is just one of many unknowns as Trump prepares to take office.
Over the last 14 months, Trump has called the diplomatic initiative "fine" -- if in need of improvements -- but he's also promised to overturn Obama's undertaking.
Analysts and experts say hints of the President-elect's eventual approach to Cuba can be found in more recent campaign trail declarations and in the personnel he's tapping to help him take office.
While they point to a slew of factors that muddy the waters -- including the Trump organization's exploration of deals in Cuba and the President-elect's own pragmatic business orientation -- many see chillier times ahead.
Advocates for the opening "had been hopeful that Trump the businessman would see the benefits," said Eric Olson, associate director of the Latin American Program at the Wilson Center. "But the closer we've gotten to him taking power, the tea leaves are a little more troublesome. It looks like things under Trump will be static or he'll make it more difficult for the Cuban government."
Roger Noriega, a visiting fellow at the American Enterprise Institute and critic of the opening to Cuba, said it's a good bet that Trump's administration will "review the strategy and at the very least freeze the efforts to loosen regulations and maybe even roll back regulations, and that will introduce enough uncertainty into this thing that it will halt any forward movement on the normalization track."
And at the US-Cuba Trade and Economic Council, which has provided information and analysis to Trump advisors and his transition team, president John Kavulich said his group thinks Trump will re-impose some restrictions.
"Our expectation is that the Trump administration won't actively seek to reverse any of the Obama administration initiatives," Kavulich said, "but they will probably add conditionality to standing initiatives," making them contingent on Cuba meeting requirements on human rights, for example.
The US-Cuba normalization, announced on December 17, 2014, doesn't lift the 1962 embargo that banned all exports to Cuba except medicine and food. That can only be lifted by Congress. But Obama used executive orders to loosen travel and trade restrictions, lift some limits on remittances and allow US banks' greater access to Cuba. In 2015, both countries to re-established embassies and the US removed Cuba from a list of state sponsors of terror.
The White House said its goals were to promote government interaction, contacts between the US and Cuban peoples, Cuban integration into international and regional systems, and greater respect for human rights, freedoms and democracy.
In a statement after Castro's death, Obama said history would judge "the enormous impact of this singular figure on the people and world around him."
Both Obama and Secretary of State John Kerry offered condolences to the Cuban people, with Kerry adding that Castro "influenced the direction of regional, even global affairs." Both were criticized for not directly referring to Castro's oppression or human rights abuses.
In contrast, Trump sent out a tweet that simply noted "Fidel Castro is dead!" Hours later, his team sent out a statement assailing the Cuban leader for his brutality.
Some of the Obama administration's hopes for the Cuba agreement were symbolized in the American Airlines flight that landed in Havana Monday morning, the first direct flight in more than 50 years. Shortly after it landed at Jose Marti International Airport, Trump tweeted that "if Cuba is unwilling to make a better deal for the Cuban people, the Cuban/American people and the U.S. as a whole, I will terminate deal."
In September 2015, Trump told the Daily Caller website that "we should have made a better deal. The concept of opening with Cuba -- 50 years is enough -- the concept of opening with Cuba is fine."
But as polls showed the election getting tighter in Florida, where Trump has a home and where many oppose normalizing ties with Cuba, the Republican candidate started hardening his stance. According to 2014 US Census figures, 35% of Miami-Dade residents are Cuban-Americans.
In July, Trump told a group of Republicans there that he would close the newly opened US Embassy in Havana and reverse Obama's steps. Trump went on to win Florida by just over 1%.
The argument that Trump's policies may be influenced by a desire to preserve opportunities in Cuba for the Trump Organization, including golf courses, condominiums and hotels, is "absurd," said Kavulich.
He pointed out that Cuba lacks many of the qualities Trump's group seeks, including developed infrastructure, a wealthy government elite, a prosperous middle class and a rapid return on investment.
Polls have shown broad approval for Obama's opening. The Pew Research Center in January found that 63% of Americans approved of re-established diplomatic ties with Cuba, while 28% disapproved.
Even so, since his victory, Trump has appointed key figures for his staff and transition who have a strong anti-Cuban track record, including Reince Priebus, his incoming White House chief of staff; retired Gen. Michael Flynn, the future national security adviser, and Kansas Republican Rep. Mike Pompeo, who has been nominated to head the CIA.
Members of his transition team are also known for conservative views on Cuba, including Robert Blau, a former assistant secretary of State and Cuba hawk, who will help manage the transition at the State Department, and Mauricio Claver-Carone, who will assist the transition at the Treasury Department.
And Trump's lack of foreign policy experience may prompt him to turn for guidance to Congress, where Cuba hawks such as Republican Sens. Marco Rubio and Ted Cruz and their Democratic colleague Robert Menendez staunchly oppose any opening.
These and other critics say Obama didn't use his leverage to force enough change within Cuba. They point to repression of human rights advocates, the stifling of journalists and new limits on self-employment, among other things.
With Cuba hardliners advising Trump, there's the possibility for increased friction, said Peter Schecter, director of the Atlantic Council's Latin America Center. Obama's move to open relations robbed the Castro regime of its fail-safe excuse for all that ailed Cuba -- the United States.
In the wake of his brother's death, President Raul Castro is likely to crack down on dissent to show that the island's revolutionary leader might have died but that the regime lives on. That might spark outrage and a reaction from Trump's circle of advisors.
"It will be important for the United States and particularly the new government of the United States not to take the bait and make mistakes," Schecter said, "because now more than ever Cubans have to own what happens on their island."
On the economic front, Risa Grais-Targow, director of the Eurasia Group's Latin America desk, said Trump could roll back diplomatic relations, re-impose the cap on remittances or condition his policy on Cuba meeting human rights standards it will almost certainly fail.
At the US-Cuba Trade and Economic Council, Kavulich said his group thinks Trump may impose conditions or further restrictions on travel and trade. "It's quite likely there will be an increase in enforcement by the Office of Foreign Assets Control and by US Customs and Border Protection," he said.
And it would be easy to do, said the Wilson Center's Olson, since Obama made these changes through executive order.
"Government by executive order is easily reversed by the next president," he said.
While there may be pushback from the US Chamber of Commerce and the major American companies that currently do business there, it may not be enough to sway Trump.
The chamber and individual businesses will "have to weigh the multitude of issues they'll want to deal with Trump on, and this may not be the one they want to lay down on the track for," Olson said.
CORRECTION: This article has been updated with the correct percentage of Miami-Dade residents who are Cuban-American.