The White House has refused to comment on Alexander's pending retirement. But it's been scheduled for the spring of 2014 since around that time the year before. It was announced shortly before former NSA contractor Edward Snowden defected with a cache of agency documents, easily the biggest scandal of Alexander's eight-year tenure at the position.
His replacement, Michael S. Rogers is not to be confused with Mike J. Rogers a U.S. Republican Representative from Michigan. Mike J. Rodgers was the chair of the House Intelligence Committee and likely Snowden's biggest enemy in Congress. This latter Rogers has a long history of bombastic statements, like claiming Snowden was helped by Russian spies, hinting he could be a Chinese spy himself, and describing the archetypical online privacy activist "a 14-year-old tweeter in the basement."
Obama made some waves in December when he announced he wouldn't separate leadership of the NSA and U.S. Cyber Command, a military organization devoted to cyber attacks and defense, which Alexander has headed since its 2009 creation. That surely helped Rogers's candidacy, as he also is the former head of the Navy's Fleet Cyber command, the Navy's contribution to the program.
Photo by seier/Flickr (Remix by Fernando Alfonso III)