By resigning on his own terms, Fidel Castro today defeated official US policy to unseat him and his government.
I read many commentators say that Raul Castro (or Carlos Lage) will bring democracy to the island. I say they won't.
With Cuba, it's important to notice that, unlike democracies, the government is legitimated by the Revolutionary Army (FAR). (With a democracy, of course, the government is legitimated by the people).
To understand why the Revolutionary Army will never peacefully yield its authority to legitimate Cuban governments, one needs to understand the way in which the U.S. Government marginalized--indeed, allowed noble FAR forces to starve to death--in the aftermath of the 1898 War.
That does not mean that the next Cuban government will not enact democratic reforms.
They surely will, although I highly doubt we'll see significant changes in the judicial process, such as an end to summary executions and other procedural reforms many good Cuban lawyers would like to see, not at least until the US Government officially abandons its attempts to subvert the Cuban government by coercing her citizens.
To be honest, with the delicate security implications alive today, such as Cuba's connection to Hezbullah and Syria, I am not sure exactly what policy changes the U.S should make, but it cannot be a wise thing to let the Cuban people on the island drift closer to our Arab foes.