WWE is at the tail end of John Cena's Last Time is Now Tournament. So far, Gunther and LA Knight have advanced to the finals and are set to square off on the upcoming episode of WWE SmackDown.The winner of this bout will face Cena on December 13. However, in a massive turn of events, Brock Lesnar might surprisingly emerge as The GOAT's final opponent, even though he is not part of the contest.The Beast Incarnate has been running a part-time schedule with the Stamford-based promotion and has made only sporadic appearances so far this year. He was also part of John Cena's Retirement Tour and faced him at Wrestlepalooza.Given that fans were disappointed with Brock Lesnar's questionable and one-sided victory over The Franchise Player in Indianapolis, the authorities might consider having the veterans run it back one last time. Arguably, this could allow Cena to get back a win over Lesnar.To pull the trigger on this move, the 48-year-old superstar might take out Gunther backstage and take his place in the finals of John Cena's Last Time Is Now Tournament. Interestingly, he could beat LA Knight and emerge as The GOAT's final opponent.Moreover, The Ring General once revealed that Brock Lesnar sits atop his list of dream opponents. Hence, the creative team may consider using this storyline to set up a feud between Lesnar and Gunther, ultimately giving fans the match they have been eagerly anticipating.However, this angle is speculative as of this writing, and nothing is confirmed. Only time will tell if this comes to fruition.John Cena reveals plans immediately following his last WWE matchNearly 17 months after announcing his plan to retire, John Cena will be wrestling his final match at Saturday Night's Main Event XLII on December 13. However, the GOAT has now revealed what's next for him after the upcoming event in Washington, D.C.Recently, on Jimmy Kimmel Live, Cena opened up about his retirement and shared his reflections on his farewell tour. When asked by Kimmel about his post-retirement plans, The Last Real Champion responded:"That night, I'm going to spend a lot of time with folks I love, who I connect strongly with. I think the next day, I hope to wake up hungover."That said, it will be interesting to see what the Stamford-based promotion has in store for John Cena's retirement match at the Capital One Arena in SNME.