But while Havana says it wants to boost foreign investment, obstacles remain. The approval process for investment projects can be long and cumbersome, and pilferage, disincentives to productivity and government intervention can cut into efficiencies. Foreign companies also pay a sky-high payroll tax.
Feinberg, who wrote a report on foreign investment in Cuba published this month by the U.S. think tank the Brookings Institution, said that while a number of foreign companies are successfully doing business with the island, others have run into problems, sending a chilly message to would-be investors. In particular he noted the recent cases of a government takeover of a food company run by a Chilean businessman accused of corruption, and contentious renegotiations of a contract with Dutch-British personal and home care products giant Unilever amid shifting government demands.
"The Cuban government has to decide that it wants foreign investment unambiguously. I think now there seem to be divisions among the leadership," Feinberg said. "Some are afraid that foreign investment compromises sovereignty, creates centers of power independent of the leadership or is exploitative."
He estimated Cuba has left on the table about $20 billion in missed investment over the past decade by not following practices typical of other developing nations. Instead, Cuba received $3.5 billion in foreign investment in that period.
Experts say a worst-case scenario for Chavez wouldn't automatically translate into the oil spigot shutting off overnight.
If Chavez's hand-picked successor, Vice President Maduro, were to take office, he would likely seek to continue the special relationship.
Opposition leader Henrique Capriles has said he wants to end the oil-for-services barter arrangements, but could find that easier said than done should he win. The two countries are intertwined in dozens of joint accords, and poor Venezuelans who benefit from free care by Cuban doctors would be loath to see that disappear.
"You can't flip the switch on a relationship like this," said Melissa Lockhart Fortner, a Cuba analyst at the Pacific Council on International Policy, a Los Angeles-based institute that focuses on global affairs. "It would be terrible politics for him. ... Switching that off would really endanger his support far too much for that to be really a feasible option."
For Cuba, Chavez's latest health scare capped off a year of disappointments in the island's attempt to wean itself from Venezuelan energy.
Three deep-water exploratory oil wells drilled off the west coast failed to yield a strike, and last month the only oil rig in the world capable of drilling there without violating U.S. sanctions sailed away with no return in sight.
Yet time and again Havana has shown that it's nothing if not resilient, weathering everything from U.S.-backed invasion and assassination plots in the 1960s to the austere "Special Period" in the early 1990s, when the Soviet collapse sent Cuba's GDP plummeting 33 percent over four years. When hurricanes damaged the country's agriculture sector and the global financial crisis squeezed tourism four years ago, Cuba tightened its belt, slashed imports and survived.
"Some people are saying the demise of Chavez is also going to be the demise of Communism in Cuba because the regime's going to collapse and the people are going to rise up," Feinberg said. "That's probably yet another delusion of the anti-Castro exile community."
Still, many Cubans are nervously tuning into the near-daily updates about Chavez's health, carried prominently in state media.
"I don't know what would happen here," said 52-year-old Havana resident Magaly Ruiz. "We might end up eating grass."
Associated Press writers Andrea Rodriguez and Anne-Marie Garcia in Havana contributed to this report.
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