Cuba is poor only partly because of the embargo and the problems caused by the US. There is also an entrenched bureaucracy in the Castro government that favors some citizens greatly over others, and the fact is that Cubans are just not as laborious as the Chinese. Immigration to the US has lured many of the most adventurous young minds to the US, where most of them are laboring feverishly in craqppy jobs so as not to get their Firebirds and Camaros repossessed, or in the case of only the most clever, their homes repossessed.
It is also true that if Cuba were as open to the US as the Juniorbushies would like, it would be forced to return assets confiscated in the 1960's to not their previous owners, who are nearly all deceased, but to the heirs of their previous owners, and elections would have to be held in which US electioneering firms would be hired to shill for one candidate or another.
The system we have in this country is barely democratic. Last time we got to choose between one Bonesman and another Bonesman for president and many of the zillionaires in the Congress and the Senate were either unopposed or were opposed by only token opposition candidates.
If these standards were applied to Cuba, it would not be even a minimal democracy.