It's starting to look like Logan Paul and John Cena will be in Los Angeles for WrestleMania 39. Unfortunately, these two will not be fighting each other, as earlier reports suggested. Instead, the two "obvious" names will each be squaring up against different opponents. Cena, in particular, might have a showdown with Austin Theory.

Fightful Select reports that the WWE originally planned for Cena vs. Paul for WrestleMania 39. This would explain the back and forth between the two following Paul's performance at last year's Crown jewel event.
But, sometime in December, the WWE changed its plans to pivot more towards Cena vs. Theory and Paul vs. Seth Rollins. The report didn't explain why the WWE was making changes to its original plans.
In terms of storyline, a Theory vs. Cena match-up at WrestleMania 39 makes more sense than Cena vs. Paul. It's worth noting that Theory hasn't been able to keep Cena's name out of his mouth for a long time.
Additionally, wrestling audiences have frequently compared Theory to Cena. Not to mention, he's the current holder of the United States championship belt - a title synonymous with Cena's earlier years. Obviously, the whole thing has a "passing of the torch" element.
With that said, the WWE is making it clear it's only a matter of time before it makes Theory vs. Cena official in April. Theory recently confirmed that he'll be there when Cena appears in front of his home state on the March 6 episode of RAW.
As one of the WWE's fastest-rising stars, a match-up against a WWE legend like Cena at WrestleMania 39 could take him over the top.
After minimal involvement with the WWE last year, likely due to his role as Peacemaker in the DC Universe, Cena is shaping up to appear more frequently this year. Cena is a major part of the WWE 2K23 Showcase Mode.
Finally, Cena isn't returning to the DCU anytime soon but he's still part of James Gunn's newly-formed cinematic universe as the violent justice-crazed vigilante.