Raul Castro will probably take over, though he's not the only contender. If he does, I wonder if his economic reforms will work out as well as he hopes and if he'll be able to control the political consequences.
Say what you will about Fidel, and there's plenty bad to say, but I find it hard to get too down on a man who raised so many of his countrymen out of poverty, who provides universal healthcare, and whose country's main export these days is doctors.
UPDATE Feb 24:
** Raul Castro named Cuban president
** Raul Castro Will Succeed Brother as President of Cuba (Update3)