On Thursday, Cuban officials said the island was still dealing with the aftermath of the killer storm and needed to postpone long-held plans for Castro, 86, to retire on February 24, 2018, when his second five-year term ends.
It was to have been the first time that Cuba was ruled by a leader not named Castro since the 1959 revolution that swept Raul Castro's older brother Fidel Castro to power.
The wrath of Irma, however, delayed the Communist-run island's single party elections process, which appoints the Cuban National Assembly that in turn selects Cuba's president.
At a meeting of the National Assembly on Thursday, Cuban state-run media announced the naming of Castro's successor will now take place April 19.
"My second and last term will have concluded," Castro told Cuban lawmakers on Thursday, "and Cuba will have a new president."
While no one seemingly has a lock on the job, Raul Castro has for years indicated that Cuban first Vice President Miguel-Diaz Canel has his blessing.
"Comrade Diaz-Canel isn't upstart or an improvisation," Castro said in 2013 when he first announced his plans to step down. "His trajectory has lasted nearly 30 years."
Born in 1960, Diaz-Canel presents a comparatively younger, more modern figure than the aging generals who for decades have held power on the island.
He is rumored to like rock 'n' roll music, which was banned in Cuba in the early days of the revolution, and has been seen reading from an electronic tablet during government meetings.
A new leader in Havana could provide a badly needed reset for US-Cubans relations, which improved under President Obama but then were rolled back by the Trump administration.
Castro "is leaving now, I wonder why?" Trump told a hardline anti-Castro crowd in Miami in June when announcing his new tougher Cuba policy.
Still, some Cubans wishing for a more moderate leader had their hopes dashed when this summer a video mysteriously leaked that showed Diaz-Canel endorsing hardline views in a closed-door government meeting.
In the video, Diaz-Canel bashes Cubans who celebrate Halloween for copying Americans, threatens to shutter an independently run magazine and vows to take on Cuba's historic nemesis, the United States.
"It was the government of the US that invaded Cuba, that put the blockade," Diaz-Canel said in the video. "They have to resolve these things to have normalized relations. We don't have to give anything in exchange."
If he's named president, it's not clear how much power Diaz-Canel will wield, because Castro is still expected to retain the powerful title of first secretary of the Cuban Communist Party until 2021.
But Cuban officials told CNN that Castro is prepared to turn over the day-to-day operations to a new leader and may spend his quasi-retirement on the other end of the island, in Santiago de Cuba, the city where his brother Fidel was buried after he died in 2016.
"I think he will exercise some control in the background," said former Cuban diplomat Carlos Alzugaray. "But he will basically tell Diaz-Canel 'This is your ballgame. You decide.' "