WWE was close to moving Roman Reigns from Raw to Smackdown during the Superstar Shake-Up. Vince McMahon has name-dropped Roman when speaking with investors and promoting the talent shake-up. Management decided at the last minute against it as it would require to move Braun Strowman and Brock Lesnar also.
The main storyline for WWE over the next few months will be Reigns and Strowman. That will lead into the next major program with Brock Lesnar, which will run until WrestleMania 34.