30 years of Cuban blockade did not work.
Did not work for what?
The goal of the blockade was to topple communist regime in Cuba. Did it work? No. Is Castro's family still in power? Yes. What exactly did the blockade do? Nothing.
The only way to deal with "closed-out" countries like Cuba or North Korea is to make them open, to show people how they can live free -- not through the government-controlled TV. Remember "Golos Ameriki"?