This may be the best news for Cuba yet.

Castro's nominated successor is his younger brother, Raul. If he does indeed succeed, it remains to be seen just how strong a hold he can keep on Cuba.
For sure, with free and fair elections, and a democratically elected government, Cuba could even have U.S. trade sanctions lifted. Then if they kept away from international politics, their tourism, trade, and prosperity potential is enormous.

Some say he's dead and I tend to agree with them.

Some say his brother Raul is more radical than Castro.

And he hasn't stepped down permanently (well, at least according to his written statement), it's temporary while he gets some rest after his operation.