According to Dave Meltzer in the latest Wrestling Observer Newsletter, RAW and SmackDown Live Executive Directors Paul Heyman and Eric Bischoff are also in charge of new merchandise for their respective brands moving forward. They'll also take charge of media publicity.
It's said that their jobs are very different from past head writers like David Kapoor, Ed Koskey, or Road Dogg and that while they'll report to Vince McMahon directly, they're accountable for the respective brands' interactions with the rest of the departments in WWE.
In terms of creative, Heyman is going to start taking charge of RAW and will be pitching ideas to Vince. While Koskey us set to remain as head writer, it's Heyman who is going to be pushing the show in a certain direction. However, it will ultimately be down to Vince to decide where things go next so things aren't really all that different!
Both Heyman and Bischoff are considered major executives in the company now, though, so it does seem like their roles aren't just to try and draw interest from fans.