John Martin sure looks like Time Warner CEO Jeff Bewkes’ heir apparent with this move, which will put him in charge of Turner Broadcasting System on January 1. Currently Time Warner’s Chief Financial and Administrative Officer, he’ll replace TBS chief Phil Kent who has run the operation Phil Kent Leaving Turnersince 2003 and now will become the unit’s chairman “for a transition period,” according to today’s release. Bewkes says that Kent initiated the change. They decided that “now is the right time to announce the next generation of leadership.” There’s no mention, though, about how the change might affect David Levy, who’s TBS’ president of sales, distribution and sports — and was widely seen as Kent’s likely successor. Bewkes says that Martin “is one of the most capable and strategically minded executives I know” adding that he’s also “a broad and thoughtful business thinker whose inclusive management style and focus on driving the business forward will fit well with the Turner tradition.” The company says that it will name Martin’s successor “in the coming weeks.” Although Martin has extensive experience handling financial matters, this will be the first time he’ll run such a large creative enterprise. TBS also is at the center of Time Warner’s growth plans, especially after the company spins off its Time Inc magazines. The Turner networks — which include TBS, TNT, and CNN — are worth about $54.6B, or 60% of Time Warner’s current value with publishing, Sterne Agee analyst Vasilly Karasyov estimated last month. But the operation faces several challenges: TNT and TBS haven’t found shows that generate the kind of loyalty and excitement that other networks have discovered, including AMC with Mad Men. At CNN, Jeff Zucker is making big moves to revive ratings. Turner also is still figuring out how deeply it wants to invest in sports; it already has deals with the NBA and Major League Baseball. Martin says that the company “is known for its innovative culture and focus on delivering programming that audiences love and count on. I look forward to working more closely with everyone at Turner to create more opportunities for consumers, advertisers, and our distribution partners.”