John Cena lost the Undisputed WWE Championship to Cody Rhodes at SummerSlam. The 17-time world champ turned face on SmackDown before the two-night event, altering the dynamic for the rematch.Now that his record-breaking title run is over, his field of opponents for the rest of his retirement tour shrinks. Brock Lesnar returned to the company at the end of the weekend, hitting his rival with an F5.Once those two conclude their feud, attention turns to the final stars Cena will face in his illustrious career. He's already battled names from his past, including CM Punk, Randy Orton, and Rhodes.Certain stars make more sense to receive the honor of being the last person Cena faces in the ring. The next four WWE stars are optimal as his final opponent, while two others are not.#4. Revisiting history with Austin Theory would do wondersAustin Theory idolized John Cena growing up. The two faced off at WrestleMania 39, with Theory beating his childhood hero. However, he didn't win clean. A-Town Down Under finally disbanded after months of tension.When the former US Champion returns to action, he should be a face. There are enough arrogant young stars on the main roster (Dominik Mysterio, Carmelo Hayes, Grayson Waller) and in NXT (Lexis King, Ricky Saints, Ethan Page).There's no reason why Theory couldn't request another match after admitting he was wrong in the past. Putting the Atlanta native over would do wonders for his career since it's stalled lately.#3. Drew McIntyre doesn't like John CenaDrew McIntyre has a history with John Cena, and he even blasted the legend for placing himself into the Elimination Chamber Match. That wasn't explored while Cena was a heel, but WWE can pick the sentiment up for one final feud.The Scottish Warrior can match The Cenation Leader on the mic, so he wouldn't be out of his element in a high-profile feud.He's also due for a respectable run as champ after getting cheated out of the title several times due to his issues with CM Punk. Beating Cena could get McIntyre back on the right path toward a title instead of facing a musician at a big premium live event.#2. Logan Paul doesn't need the pushSomeone who doesn't need putting over or the rub associated with such a high-profile spot is Logan Paul. The two teamed together at Money in the Bank but clashed due to their egos.The Maverick will probably take another break from WWE until the next show in Saudi Arabia or WarGames. That's too much time off with so many other deserving stars who could oppose Cena.The social media influencer only returns for one-off feuds, so it would come and go faster and probably wouldn't be as memorable as other potential angles.#2. Gunther would have faced Cena during the prime of his careerBoth Gunther and Cena lost their titles at SummerSlam. The Ring General will miss time with a facial injury, while Cena will have to deal with Brock Lesnar again.There was a time when Gunther would have been thrown to the wolves against Cena under Mr. McMahon's guidance. Cena stamped out Rusev's momentum as a heel in WWE, and it took years for him to recover.The Ring General already has two reigns as World Heavyweight Champion under his belt. Defeating the person who personified sports entertainment, something Gunther has said he despises, would help repair his image.#1. Bron Breakker is the future of WWE View this post on Instagram Instagram PostPaul Heyman and Seth Rollins have said it numerous times since joining up - Bron Breakker is the future of the wrestling industry. He's already won the NXT and Intercontinental Titles in his young career.Joining up with The Visionary and The Oracle continues that narrative. It will likely be a push similar to when Roman Reigns was shoved down fans' throats as WWE's top face.Breakker, however, is already over with fans as they bark when he's on screen. With Rollins holding the World Heavyweight Title, he'll have to bury the face of the past to make way for the face of the future.#1. Roman Reigns shouldn't get the honorThe time of putting Roman Reigns over the rest of the roster has passed. He had his time in the sun for nearly a decade and wasn't pinned in nearly four years. The constant pushes often held part of the roster back as the lone major champion.He works a part-time schedule and took off yet again after a big win at SummerSlam. Reigns is too busy with Rollins and Heyman to worry about doing anything with Cena.Factor in that The Tribal Chief will only be back, probably, one more time this year, and there's little to no time for a meaningful program.Beating Cena wouldn't only help further boost Reigns' profile, instead of paying it forward for the future. Cena should put over someone in WWE who needs/could use it. Reigns doesn't fit that profile.