The U.S. media's analysis of Raul is either intentionally false, doesn't believe the population can understand the complexity of Cuban politics given the decades of lies we've been told, or else just really really bad. (I believe all three)
There are more popular, more charismatic, and more capable leaders in high office already in Cuba ready to step in. Fidel can't run a country on his own. He's a figure head. Raul isn't very popular either - Fidel is. Raul has always been the more hard core Stalinist of the original revolutionary leadership. The media is setting people up for a fall by feeding them info otherwise.