Discovery’s chief executive David Zaslav has taken the first big step to overhaul its business after it acquires WarnerMedia, the company behind Casablanca, Friends and Game of Thrones, installing his lieutenants as senior leaders of the combined group.

JB Perrette, who has led Discovery’s international and streaming businesses, is set to take on one of the biggest jobs in entertainment: running the streaming businesses of the combined Warner-Discovery. Kathleen Finch, another Discovery executive, will run the television channels including TBS and TNT, while Discovery’s chief financial officer, accounting officer and people officer will hold the equivalent jobs at the new group.

The $43bn merger of Warner and Discovery, which is set to close as early as Friday, is the latest era-defining mega-deal for Hollywood, as traditional media fights for survival in the entertainment business whose future will be ruled by streaming.