Cuba let 20% of the population leave in 2020-24 so that they would have fewer dissenters in the country who might overthrow the government. Thats a higher rate of population per year than the peak of the great Irish famine
The single biggest problem would be rebuilding the US manufacturing base. Once that happens, the US would be fine. America's probably capable of autarky: it's got the natural resources, population size, and technology.
The US didn't impose the condition of being a resource-poor island on Cuba, nor did it impose the condition of economic mismanagement on it (apparently so bad even the Soviets complained about it). The US imposed the condition of a trade embargo, and that's it.
The cuban government via National Office of Statistics and Information admitted it fell by at least 10%, but have not done a census in 15 years. Independent estimates range form 18-24%.