I don't think much will change with Castro stepping down. His brother though is more open to the idea of free markets, which is kind of supprising since during the revolution he was the propoent for communisim in the extreme (more than Fidel). I don't think the embargo will be lifted untill a lot of political issues have been resolved such as reparations for land, human rights violations and so on. Without those issues addressed the US will not change its policy due to its large cuban-american lobbying group.