Zehme's book is yet to be published owing to numerous delays, presumably the publication will now tie in with the release or pre-release of some material from the series.
NBC have not announced any further details including who would be playing Carson.
Carson was one of NBC's biggest stars, working for the company for over thirty years. His show, 'The Tonight Show With Johnny Carson', was hugely popular and aired on the network between 1962 and 1992.
He retired in 1992 and has been cited as the inspiration for many other talk show hosts including David Letterman, Jay Leno and Jimmy Fallon.