CNN says the news is false. I believe the rumour was made to make a joke out of Jay Leno replacing Conan, of course. Piers Morgan taking over was a shitty idea anyways.

More on it here:

http://latimesblogs.latimes.com/showtracker/2010/06/cnn-says-reports-that-larry-king-is-close-to-being-replaced-are-untrue.html

Kev