Cuba is poised at the brink of change. After more than 45 years in power, Fidel Castro, now 80, has relinquished power to his brother Raúl. But with the old communist firebrand still making an occasional taped TV appearance and publishing political commentaries — and probably operating behind the scenes as well — the real post-Fidel era likely will have to await his death. The former Soviet ally has been a thorn in the sides of successive U.S. administrations — and during the 1962 Cuban missile crisis brought the world to the brink of atomic war. Now Washington worries whether his death could provoke instability in Cuba leading to a mass exodus toward Florida's nearby shores. Cuban-Americans, meanwhile, are debating what role to play if they're allowed free access to the island. And U.S. businesses are wondering if warmer relations with Cuba could finally end the long-running U.S. trade embargo — allowing unfettered access to 11 million Cuban consumers.