The enmity between the United States and Cuba is well known and is unlikely to change anytime soon, as least on a government-to-government level. This report from NBC News notes that lower-level private approaches may succeed in establishing new links between the two countries.
If you are interested in digging deeper, this panel report from the Center for Strategic and International Studies examines the current state of the Cuban economy, the outlook for future development and investment, and the potential for evolution toward a more open system. Perhaps if private individuals and philanthropic groups are successful at establishing sustainable ties with Cuba then the U.S. government may find it easier to develop a rapprochement with Cuba in the early years of a post-Castro era.