You’ve read all of your free items this month. To register, get added benefits and unlimited access to articles, Become a Member. Already a Member? Sign in. Advertising Age Article Abstract David Letterman to Leave 'Late Show' in 2015 Broadcast Late-Night Transformation Nearly Complete By Nat Ives, Published on April 03, 2014 1 Want more Access, Content & Connections? Upgrade to Membership. We are glad you are enjoying Advertising Age. To get uninterrupted access and additional benefits, become a member today. Become a Member Already a member? Log in.