According to Meltzer.
Here's what's going to happen. John Cena turns heel against AJ Styles, who turns face. The Club and Finn Balor come out and throw a chair into the ring while the ref is down. AJ refuses to use it, wanting to earn respect by beating Cena clean. Cena uses it and starts Smackdown Club. Too sweets all around. Fast forward to the Rumble. One entrant left to come out and it's down to Undertaker, Brock and Goldberg. Brock and Goldberg eliminate each other, setting up their mania match. Everyone thinks Taker's going to win and face Cena at Mania in his last match. The buzzer for #30 sounds. Wait! Is it? Can it be!? The dirtiest player in the game, Ric Flair, struts down to the ring and tosses the Undertaker over the top rope. Flair spends the next two months doing promos about how his record will never be broken. Whoever loses out of Cena-Flair at Mania retires. Cena, who never gives up, taps out to the figure four and retires to star in buddy cop movies with The Rock. Two nights later on Smackdown, Flair retires as the record 17-time world champion, vacating the belt so that his protege AJ can get back what he never rightfully lost. As he goes to hand over the belt, Samoa Joe's music hits and he rushes to the ring, hitting the muscle buster on AJ and holding the WWE Championship aloft.