Roman Reigns is the Head of the Table in the WWE and he's undoubtedly booked to headline WrestleMania for the fourth straight year in a row to shatter records held by the likes of Hulk Hogan or John Cena.
Big speculations are going on the Road to WrestleMania 40 on the main event match of the biggest premium live event of the year and two options are reportedly on the table - Roman Reigns vs. The Rock or Roman Reigns vs. Cody Rhodes.

While the above two matches are being discussed by the WWE creative, the Wrestling Observer is reporting that another interesting option is being discussed as a possibility for the Night Two main event featuring all these three names.
Roman Reigns vs. The Rock vs. Cody Rhodes in a Triple Threat Match for the Undisputed WWE Universal Championship could end up becoming the Night Two main event of WrestleMania 40 in Philadelphia but nothing is set in stone, as of this writing.
There was a point following The Rock's Day 1 appearance on Raw where many believed that he could be booked to go in a war against Roman Reigns at Elimination Chamber which isn't possible either since the latter isn't going to Australia for the PLE.
On the other hand, Cody Rhodes and 'his story' has long been a discussed topic within the WWE Universe as the angle essentially sets up an automatic rematch with Roman Reigns after The Bloodline ruined his shot, last year.
During an interview with Sports Illustrated, AEW wrestler Dustin Rhodes also noted why his brother Cody should headline the 40th anniversary of WrestleMania for the undisputed WWE Title or else their family legacy could be hampered.
"I hope Cody's in the main event spot against Roman. Or it's going to be The Rock. If it is The Rock, I'm pi**ed - this is Cody's time. He is becoming the face of the company, and it's paying off. But I get it."
Another legend Diamond Dallas Page said that Cody is the new People's Champion, essentially comparing him to The Rock who is also back in the WWE fold. That being said, it's going to be a tough choice for Triple H & Co. to decide the marquee match for WrestleMania 40.