#2 Roman Reigns defeats Brock Lesnar (WWE WrestleMania 38)
Well, it's probably going to happen. And this time, it will be great. Brock Lesnar would go on to have a typical reign with the Universal Championship. One of the biggest matches he can have is a Champion vs. Champion match at Survivor Series, against Bobby Lashley, who could possibly hold the WWE Championship at the time. But the main story is with Roman Reigns.
In what will be a 'Battle of the Paul Heyman guys', Reigns and Lesnar will destroy each other after realizing that they cannot co-exist under Heyman's management. After the Big Dog wins the 2022 Royal Rumble match, he could set his sights on the man he failed to beat in two attempts at WrestleMania.
Roman Reigns defeated Brock Lesnar at SummerSlam 2018, but this would be the emphatic statement victory WWE has always wanted him to have over The Beast. It would also serve as a redemption for their lackluster main event at WrestleMania 34. In the end, the 'Tribal Chief' could win the Universal title with some help from his "special counsel".
This would be a huge development, with Roman Reigns facilitating the end of the legendary partnership between Lesnar and Heyman. The latter's new act with Reigns could possibly reach a similar level if WWE handles it carefully over the years. After this, there is no doubt about who the biggest star in WWE is.